iOS开发小技巧合集-白红宇

本文主要记录日常工作中积累的一些iOS小技巧

SDWebImage 加载大量高清图片时内存暴增
- 解决方案：关闭SD加载高清大图时的解压缩

static BOOL SDImageCacheOldShouldDecompressImages = YES; static BOOL SDImagedownloderOldShouldDecompressImages = YES; - (void)viewDidLoad {   [super viewDidLoad];   // 关闭SD加载高清大图时的解压缩     SDImageCache *canche = [SDImageCache sharedImageCache];     SDImageCacheOldShouldDecompressImages = canche.shouldDecompressImages;     canche.shouldDecompressImages = NO;     SDWebImageDownloader *downloder = [SDWebImageDownloader sharedDownloader];     SDImagedownloderOldShouldDecompressImages = downloder.shouldDecompressImages;    downloder.shouldDecompressImages = NO;   }   -(void)dealloc {   SDImageCache *canche = [SDImageCache sharedImageCache];   canche.shouldDecompressImages = SDImageCacheOldShouldDecompressImages;   SDWebImageDownloader *downloder = [SDWebImageDownloader sharedDownloader];   downloder.shouldDecompressImages = SDImagedownloderOldShouldDecompressImages;   } 复制代码

SDWebImage本地缓存有时候会害人。如果之前缓存过一张图片，即使下次服务器换了这张图片，但是图片url没换，用SDWebimage下载下来的还是以前那张，所以遇到这种问题，不要先去怼服务器，清空下缓存再试就好了。

禁止手机睡眠

[UIApplication sharedApplication].idleTimerDisabled = YES;复制代码

隐藏某行cell

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{// 如果是你需要隐藏的那一行，返回高度为0    if(indexPath.row == YouWantToHideRow){       return 0;    }       return 44;}// 然后再你需要隐藏cell的时候调用[self.tableView beginUpdates];[self.tableView endUpdates];复制代码

禁用button高亮

button.adjustsImageWhenHighlighted = NO;或者在创建的时候UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];复制代码

动画切换window的根控制器

[UIView transitionWithView:[UIApplication sharedApplication].keyWindow duration:.5f options:UIViewAnimationOptionTransitionCrossDissolve animations:^{        BOOL oldState = [UIView areAnimationsEnabled];        [UIView setAnimationsEnabled:NO];        [UIApplication sharedApplication].keyWindow.rootViewController = [[RootViewController alloc]init];        [UIView setAnimationsEnabled:oldState];    } completion:^(BOOL finished) {    }];复制代码

去除数组中重复的对象

NSArray *newArr = [oldArr valueForKeyPath:@"@distinctUnionOfObjects.self"];复制代码

编译的时候遇到 no such file or directory: /users/apple/XXX
- 是因为编译的时候，在此路径下找不到这个文件，解决这个问题，首先是是要检查缺少的文件是不是在工程中，如果不在工程中，需要从本地拖进去，如果发现已经存在工程中了，或者拖进去还是报错，这时候需要去build phases中搜索这个文件，这时候很可能会搜出现两个相同的文件，这时候，有一个路径是正确的，删除另外一个即可。如果删除了还是不行，需要把两个都删掉，然后重新往工程里拖进这个文件即可

iOS8系统中，tableView最好实现下-tableView: heightForRowAtIndexPath:这个代理方法，要不然在iOS8中可能就会出现显示不全或者无法响应事件的问题

iOS8中实现侧滑功能的时候这个方法必须实现，要不然在iOS8中无法侧滑

// 必须写的方法，和editActionsForRowAtIndexPath配对使用，里面什么不写也行- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {}复制代码

三个比较特殊的通知

NSSystemTimeZoneDidChangeNotification监听修改时间界面的两个按钮状态变化UIApplicationSignificantTimeChangeNotification 监听用户改变时间 （只要点击自动设置按钮就会调用）NSSystemClockDidChangeNotification 监听用户修改时间（时间不同才会调用）复制代码

获取不到UICollectionView指定cell的问题

[self.collectionView layoutIfNeeded];//添加这句话就好 QTMResContinueEditeCell *cell = (QTMResContinueEditeCell *)[self.collectionView cellForItemAtIndexPath:[NSIndexPath indexPathForItem:_index inSection:0]];复制代码

跳进app权限设置

// 跳进app设置if (UIApplicationOpenSettingsURLString != NULL) {    UIApplication *application = [UIApplication sharedApplication];    NSURL *URL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];    if ([application respondsToSelector:@selector(openURL:options:completionHandler:)]) {        [application openURL:URL options:@{}           completionHandler:nil];    } else {        [application openURL:URL];    }}            复制代码

给一个view截图

- (UIImage *)cutImageWithView:(UIView *)view{    UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0);    [view.layer renderInContext:UIGraphicsGetCurrentContext()];    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();        return image;}复制代码

注意对象为nil的时候，调用此对象分类的方法不会执行

collectionView的内容小于其宽高的时候是不能滚动的，设置可以滚动：

collectionView.alwaysBounceHorizontal = YES;collectionView.alwaysBounceVertical = YES;复制代码

颜色转图片

+ (UIImage *)imageWithColor:(UIColor *)color {    //描述一个矩形    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);    //开启图形上下文    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);    //获得图形上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    //使用color演示填充上下文    CGContextSetFillColorWithColor(ctx, [color CGColor]);    //渲染上下文    CGContextFillRect(ctx, rect);    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    //关闭图形上下文    UIGraphicsEndImageContext();        return image;    }复制代码

view设置圆角

#define ViewBorderRadius(View, Radius, Width, Color)\\[View.layer setCornerRadius:(Radius)];\[View.layer setMasksToBounds:YES];\[View.layer setBorderWidth:(Width)];\[View.layer setBorderColor:[Color CGColor]] // view圆角复制代码

view某个角度设置圆角

UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.whiteView.bounds byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight cornerRadii:CGSizeMake(10, 10)];    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];    maskLayer.frame = self.whiteView.bounds;    maskLayer.path = maskPath.CGPath;    self.whiteView.layer.mask = maskLayer;      ##指定了需要成为圆角的角该参数是UIRectCorner类型的，可选的值有：* UIRectCornerTopLeft* UIRectCornerTopRight* UIRectCornerBottomLeft* UIRectCornerBottomRight* UIRectCornerAllCorners    复制代码

由角度转换弧度

#define DegreesToRadian(x) (M_PI * (x) / 180.0)复制代码

由弧度转换角度

#define RadianToDegrees(radian) (radian*180.0)/(M_PI)复制代码

获取图片资源

//建议使用前两种宏定义,性能高于后者#define LOADIMAGE(file,ext) [UIImage imageWithContentsOfFile:[[NSBundle mainBundle]pathForResource:file ofType:ext]]#define IMAGE(A) [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:A ofType:nil]]#define ImageNamed(_pointer) [UIImage imageNamed:[UIUtil imageName:_pointer]]#define UIImageName(name) [UIImage imageNamed:name]复制代码

文件路径

//获取temp#define PathTemp NSTemporaryDirectory()//获取Document#define PathDocument [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]//获取 Cache#define PathCache [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject]复制代码

GCD代码只执行一次

#define kDISPATCH_ONCE_BLOCK(onceBlock) static dispatch_once_t onceToken; dispatch_once(&onceToken, onceBlock);复制代码

自定义NSLog

//DEBUG  模式下打印日志,当前行#ifdef DEBUG#   define DLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);#else#   define DLog(...)#endif//重写NSLog,Debug模式下打印日志和当前行数#if DEBUG#define NSLog(FORMAT, ...) fprintf(stderr,"\nfunction:%s line:%d content:%s\n", __FUNCTION__, __LINE__, [[NSString stringWithFormat:FORMAT, ##__VA_ARGS__] UTF8String]);#else#define NSLog(FORMAT, ...) nil#endif//DEBUG  模式下打印日志,当前行 并弹出一个警告#ifdef DEBUG#   define ULog(fmt, ...)  { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[NSString stringWithFormat:@"%s\n [Line %d] ", __PRETTY_FUNCTION__, __LINE__] message:[NSString stringWithFormat:fmt, ##__VA_ARGS__]  delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alert show]; }#else#   define ULog(...)#endif复制代码

Font

#define FONTS(size) [UIFont systemFontOfSize:(size)]#define BOLDFONTS(size) [UIFont boldSystemFontOfSize:(size)]复制代码

//主线程#define kDISPATCH_MAIN_THREAD(mainQueueBlock) dispatch_async(dispatch_get_main_queue(), mainQueueBlock);//异步线程#define kDISPATCH_GLOBAL_QUEUE_DEFAULT(globalQueueBlock) dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), globalQueueBlocl);复制代码

通知

#define NOTIF_ADD(n, f)     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(f) name:n object:nil]#define NOTIF_POST(n, o)    [[NSNotificationCenter defaultCenter] postNotificationName:n object:o]#define NOTIF_REMV()        [[NSNotificationCenter defaultCenter] removeObserver:self]复制代码

Color

// RGB颜色转换（16进制->10进制）#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]// 获取RGB颜色#define RGBA(r,g,b,a) [UIColor colorWithRed:r/255.0f green:g/255.0f blue:b/255.0f alpha:a]//清除背景色#define CLEARCOLOR [UIColor clearColor]// 随机色#define RandomCOLOR RGBCOLOR(arc4random_uniform(256),arc4random_uniform(256),arc4random_uniform(256))复制代码

获取window

+(UIWindow*)getWindow {    UIWindow* win = nil; //[UIApplication sharedApplication].keyWindow;    for (id item in [UIApplication sharedApplication].windows) {        if ([item class] == [UIWindow class]) {            if (!((UIWindow*)item).hidden) {                win = item;                break;            }        }    }    return win;}复制代码

修改textField的placeholder的字体颜色、大小

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];// 或者textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:placeholder attributes:@{NSFontAttributeName : [UIFont systemFontOfSize:13],NSForegroundColorAttributeName : [UIColor grayColor]}];复制代码

APP缓存

/** *  存 数组数据*/+(void)setObectOfArray:(NSArray *)array fileName:(NSString *)fileName{        //缓存文件的 根路径    NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];    // 缓存 文件夹 路径    NSString *filePath = [path stringByAppendingPathComponent:@"XXX.dataCache"];        NSFileManager *fileManager = [NSFileManager defaultManager];        if ([fileManager fileExistsAtPath:filePath] == NO)    {        [fileManager createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil];    }    //缓存文件的路径    NSString * cacheFilePath = [filePath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.plist",fileName]];    BOOL isSuccess = [array writeToFile:cacheFilePath atomically:NO];    if (isSuccess) {        NSLog(@"缓存数据成功:---%@",cacheFilePath);    }else    {        NSLog(@"缓存数据失败:---%@",cacheFilePath);    }    }/***  取 数组数据*/+(NSArray *)cacheArrayForFileName:(NSString *)fileName{        //缓存文件的 根路径    NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];    // 缓存 文件夹 路径    NSString *filePath = [path stringByAppendingPathComponent:@"XXX.dataCache"];    //缓存文件的路径    NSString * cacheFilePath = [filePath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.plist",fileName]];    //取得缓存文件    NSArray *array  = [NSArray arrayWithContentsOfFile:cacheFilePath];        return array;}/*** 清除 这个全部的缓存数据 */+(void)clearCacheListData:(void (^)())completion{    // 异线程    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{        // 清楚缓存        //缓存文件的 根路径        NSString *path = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];        // 缓存 文件夹 路径        NSString *filePath = [path stringByAppendingPathComponent:@"FortuneDonkey.dataCache"];        NSFileManager *manager = [NSFileManager defaultManager];        //移除文件夹        [manager removeItemAtPath:filePath error:nil];        //  创建一个新的文件夹        [manager createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil];        if (completion)        {            //回调主线程            dispatch_async(dispatch_get_main_queue(), ^{                completion();            });        }    });}/*** 清除SD缓存数据 */-(void)clearSDCacheData{    //先清除内存中的图片缓存    [[SDImageCache sharedImageCache] clearMemory];    //清除磁盘的缓存    [[SDImageCache sharedImageCache] clearDisk];}复制代码

获取APP缓存大小

- (CGFloat)getCachSize {    NSUInteger imageCacheSize = [[SDImageCache sharedImageCache] getSize];    //获取自定义缓存大小    //用枚举器遍历 一个文件夹的内容    //1.获取 文件夹枚举器    NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];    NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:myCachePath];    __block NSUInteger count = 0;    //2.遍历    for (NSString *fileName in enumerator) {        NSString *path = [myCachePath stringByAppendingPathComponent:fileName];        NSDictionary *fileDict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];        count += fileDict.fileSize;//自定义所有缓存大小    }    // 得到是字节  转化为M    CGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;    return totalSize;}复制代码

几个常用权限判断

if ([CLLocationManager authorizationStatus] ==kCLAuthorizationStatusDenied) {        NSLog(@"没有定位权限");    }    AVAuthorizationStatus statusVideo = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];    if (statusVideo == AVAuthorizationStatusDenied) {        NSLog(@"没有摄像头权限");    }    //是否有麦克风权限    AVAuthorizationStatus statusAudio = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];    if (statusAudio == AVAuthorizationStatusDenied) {        NSLog(@"没有录音权限");    }    [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {        if (status == PHAuthorizationStatusDenied) {            NSLog(@"没有相册权限");        }    }];复制代码

系统相关的一些方法

//获取系统版本#define IOS_VERSION [[[UIDevice currentDevice] systemVersion] floatValue]#define IS_IOS10_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 10.0)//获取当前语言#define CurrentLanguage ([[NSLocale preferredLanguages] objectAtIndex:0])//判断是否 Retina屏、设备是否%fhone 5、是否是iPad#define isRetina ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 960), [[UIScreen mainScreen] currentMode].size) : NO)#define iPhone5 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size) : NO)#define iPhone6 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(750, 1334), [[UIScreen mainScreen] currentMode].size) : NO)#define isPad (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)//判断是真机还是模拟器#if TARGET_OS_IPHONE//iPhone Device#endif#if TARGET_IPHONE_SIMULATOR//iPhone Simulator#endif复制代码

长按复制功能

- (void)viewDidLoad{    [self.view addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pasteBoard:)]];}- (void)pasteBoard:(UILongPressGestureRecognizer *)longPress {    if (longPress.state == UIGestureRecognizerStateBegan) {        UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];        pasteboard.string = @"我是文字";    }}复制代码

判断图片类型

//通过图片 Data 数据第一个字节 来获取图片扩展名- (NSString *)contentTypeForImageData:(NSData *)data{    uint8_t c;    [data getBytes:&c length:1];    switch (c)    {        case 0xFF:            return @"jpeg";        case 0x89:            return @"png";        case 0x47:            return @"gif";        case 0x49:        case 0x4D:            return @"tiff";        case 0x52:        if ([data length] < 12) {            return nil;        }        NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];        if ([testString hasPrefix:@"RIFF"]            && [testString hasSuffix:@"WEBP"])        {            return @"webp";        }        return nil;    }    return nil;}复制代码

获取手机和 APP 信息

//手机序列号NSString* identifierNumber = [[UIDevice currentDevice] uniqueIdentifier];//手机别名： 用户定义的名称NSString* userPhoneName = [[UIDevice currentDevice] name];//设备名称NSString* deviceName = [[UIDevice currentDevice] systemName];//手机系统版本NSString* phoneVersion = [[UIDevice currentDevice] systemVersion];//手机型号NSString* phoneModel = [[UIDevice currentDevice] model];//地方型号  （国际化区域名称）NSString* localPhoneModel = [[UIDevice currentDevice] localizedModel];NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];// 当前应用名称NSString *appCurName = [infoDictionary objectForKey:@"CFBundleDisplayName"];// 当前应用版本  NSString *appCurVersion = [infoDictionary objectForKey:@"CFBundleShortVersionString"];// 当前应用版本号码   int类型NSString *appCurVersionNum = [infoDictionary objectForKey:@"CFBundleVersion"];   复制代码

UIImage绘制圆角

- (UIImage *)circleImage{    // NO代表透明    UIGraphicsBeginImageContextWithOptions(self.size, NO, 1);    // 获得上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    // 添加一个圆    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);    // 方形变圆形    CGContextAddEllipseInRect(ctx, rect);    // 裁剪    CGContextClip(ctx);    // 将图片画上去    [self drawInRect:rect];    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return image;}复制代码

准确获取图片像素

CGFloat fixelW = CGImageGetWidth(image.CGImage);CGFloat fixelH = CGImageGetHeight(image.CGImage);复制代码

JSON字符串转字典

+ (NSDictionary *)parseJSONStringToNSDictionary:(NSString *)JSONString {    NSData *JSONData = [JSONString dataUsingEncoding:NSUTF8StringEncoding];    NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:JSONData options:NSJSONReadingMutableLeaves error:nil];    return responseJSON;}复制代码

获取当前控制器

//获取当前屏幕显示的viewcontroller- (UIViewController *)getCurrentVC{    UIWindow *window = [[UIApplication sharedApplication].windows firstObject];    if (!window) {        return nil;    }    UIView *tempView;    for (UIView *subview in window.subviews) {        if ([[subview.classForCoder description] isEqualToString:@"UILayoutContainerView"]) {            tempView = subview;            break;        }    }    if (!tempView) {        tempView = [window.subviews lastObject];    }        id nextResponder = [tempView nextResponder];    while (![nextResponder isKindOfClass:[UIViewController class]] || [nextResponder isKindOfClass:[UINavigationController class]] || [nextResponder isKindOfClass:[UITabBarController class]]) {        tempView =  [tempView.subviews firstObject];                if (!tempView) {            return nil;        }        nextResponder = [tempView nextResponder];    }    return  (UIViewController *)nextResponder;}复制代码

KVO监听某个对象的属性

// 添加监听者[self addObserver:self forKeyPath:property options:NSKeyValueObservingOptionNew context:nil];// 当监听的属性值变化的时候会来到这个方法- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {    if ([keyPath isEqualToString:@"property"]) {       [self textViewTextChange];       } else {     }}复制代码

Reachability判断网络状态

NetworkStatus status = [[Reachability reachabilityForInternetConnection] currentReachabilityStatus];    if (status == NotReachable) {        NSLog(@"当前设备无网络");    }    if (status == ReachableViaWiFi) {        NSLog(@"当前wifi网络");    }    if (status == ReachableViaWWAN) {        NSLog(@"当前蜂窝移动网络");    }    复制代码

AFNetworking监听网络状态

// 监听网络状况    AFNetworkReachabilityManager *mgr = [AFNetworkReachabilityManager sharedManager];    [mgr setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {        switch (status) {            case AFNetworkReachabilityStatusUnknown:                break;            case AFNetworkReachabilityStatusNotReachable: {                NSLog(@"当前设备无网络");            }                break;            case AFNetworkReachabilityStatusReachableViaWiFi:                 NSLog(@"当前wifi网络");                break;            case AFNetworkReachabilityStatusReachableViaWWAN:                NSLog(@"当前蜂窝移动网络");                break;            default:                break;        }    }];   [mgr startMonitoring];复制代码

父视图透明不影响子视图的做法

self.view.backgroundColor = [[UIColor whiteColor]colorWithAlphaComponent:0.7f];复制代码

取图片某一点的颜色

if (point.x < 0 || point.y < 0) return nil;   CGImageRef imageRef = self.CGImage;   NSUInteger width = CGImageGetWidth(imageRef);   NSUInteger height = CGImageGetHeight(imageRef);   if (point.x >= width || point.y >= height) return nil;   unsigned char *rawData = malloc(height * width * 4);   if (!rawData) return nil;   CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();   NSUInteger bytesPerPixel = 4;   NSUInteger bytesPerRow = bytesPerPixel * width;   NSUInteger bitsPerComponent = 8;   CGContextRef context = CGBitmapContextCreate(rawData,                                                width,                                                height,                                                bitsPerComponent,                                                bytesPerRow,                                                colorSpace,                                                kCGImageAlphaPremultipliedLast                                                | kCGBitmapByteOrder32Big);   if (!context) {       free(rawData);       return nil;   }   CGColorSpaceRelease(colorSpace);   CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);   CGContextRelease(context);   int byteIndex = (bytesPerRow * point.y) + point.x * bytesPerPixel;   CGFloat red   = (rawData[byteIndex]     * 1.0) / 255.0;   CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0;   CGFloat blue  = (rawData[byteIndex + 2] * 1.0) / 255.0;   CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0;   UIColor *result = nil;   result = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];   free(rawData);   return result;复制代码

判断该图片是否有透明度通道

- (BOOL)hasAlphaChannel{    CGImageAlphaInfo alpha = CGImageGetAlphaInfo(self.CGImage);    return (alpha == kCGImageAlphaFirst ||            alpha == kCGImageAlphaLast ||            alpha == kCGImageAlphaPremultipliedFirst ||            alpha == kCGImageAlphaPremultipliedLast);}复制代码

两张图片合成

+ (UIImage*)mergeImage:(UIImage*)firstImage withImage:(UIImage*)secondImage {    CGImageRef firstImageRef = firstImage.CGImage;    CGFloat firstWidth = CGImageGetWidth(firstImageRef);    CGFloat firstHeight = CGImageGetHeight(firstImageRef);    CGImageRef secondImageRef = secondImage.CGImage;    CGFloat secondWidth = CGImageGetWidth(secondImageRef);    CGFloat secondHeight = CGImageGetHeight(secondImageRef);    CGSize mergedSize = CGSizeMake(MAX(firstWidth, secondWidth), MAX(firstHeight, secondHeight));    UIGraphicsBeginImageContext(mergedSize);    [firstImage drawInRect:CGRectMake(0, 0, firstWidth, firstHeight)];    [secondImage drawInRect:CGRectMake(0, 0, secondWidth, secondHeight)];    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return image;}复制代码

制作水印

// 画水印- (void) setImage:(UIImage *)image withWaterMark:(UIImage *)mark inRect:(CGRect)rect{    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0)    {        UIGraphicsBeginImageContextWithOptions(self.frame.size, NO, 0.0);    }    //原图    [image drawInRect:self.bounds];    //水印图    [mark drawInRect:rect];    UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    self.image = newPic;}复制代码

让label的文字内容显示在左上／右上／左下／右下／中心顶／中心底部

自定义UILabel// 重写label的textRectForBounds方法- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {    CGRect rect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];    switch (self.textAlignmentType) {        case WZBTextAlignmentTypeLeftTop: {            rect.origin = bounds.origin;        }            break;        case WZBTextAlignmentTypeRightTop: {            rect.origin = CGPointMake(CGRectGetMaxX(bounds) - rect.size.width, bounds.origin.y);        }            break;        case WZBTextAlignmentTypeLeftBottom: {            rect.origin = CGPointMake(bounds.origin.x, CGRectGetMaxY(bounds) - rect.size.height);        }            break;        case WZBTextAlignmentTypeRightBottom: {            rect.origin = CGPointMake(CGRectGetMaxX(bounds) - rect.size.width, CGRectGetMaxY(bounds) - rect.size.height);        }            break;        case WZBTextAlignmentTypeTopCenter: {            rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, CGRectGetMaxY(bounds) - rect.origin.y);        }            break;        case WZBTextAlignmentTypeBottomCenter: {            rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, CGRectGetMaxY(bounds) - CGRectGetMaxY(bounds) - rect.size.height);        }            break;        case WZBTextAlignmentTypeLeft: {            rect.origin = CGPointMake(0, rect.origin.y);        }            break;        case WZBTextAlignmentTypeRight: {            rect.origin = CGPointMake(rect.origin.x, 0);        }            break;        case WZBTextAlignmentTypeCenter: {            rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, (CGRectGetHeight(bounds) - CGRectGetHeight(rect)) / 2);        }            break;        default:            break;    }    return rect;}- (void)drawTextInRect:(CGRect)rect {    CGRect textRect = [self textRectForBounds:rect limitedToNumberOfLines:self.numberOfLines];    [super drawTextInRect:textRect];}复制代码

移除字符串中的空格和换行

+ (NSString *)removeSpaceAndNewline:(NSString *)str {    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];    return temp;}复制代码

判断字符串中是否有空格

+ (BOOL)isBlank:(NSString *)str {    NSRange _range = [str rangeOfString:@" "];    if (_range.location != NSNotFound) {        //有空格        return YES;    } else {        //没有空格        return NO;    }}复制代码

获取一个视频的第一帧图片

NSURL *url = [NSURL URLWithString:filepath];AVURLAsset *asset1 = [[AVURLAsset alloc] initWithURL:url options:nil];AVAssetImageGenerator *generate1 = [[AVAssetImageGenerator alloc] initWithAsset:asset1];generate1.appliesPreferredTrackTransform = YES;NSError *err = NULL;CMTime time = CMTimeMake(1, 2);CGImageRef oneRef = [generate1 copyCGImageAtTime:time actualTime:NULL error:&err];UIImage *one = [[UIImage alloc] initWithCGImage:oneRef]; return one;复制代码

获取视频的时长

+ (NSInteger)getVideoTimeByUrlString:(NSString *)urlString {    NSURL *videoUrl = [NSURL URLWithString:urlString];    AVURLAsset *avUrl = [AVURLAsset assetWithURL:videoUrl];    CMTime time = [avUrl duration];    int seconds = ceil(time.value/time.timescale);    return seconds;}复制代码

当tableView占不满一屏时，去除下边多余的单元格

self.tableView.tableHeaderView = [UIView new];self.tableView.tableFooterView = [UIView new];复制代码

isKindOfClass和isMemberOfClass的区别

isKindOfClass可以判断某个对象是否属于某个类，或者这个类的子类。isMemberOfClass更加精准，它只能判断这个对象类型是否为这个类(不能判断子类)复制代码

禁用系统滑动返回功能

- (void)viewDidAppear:(BOOL)animated{     [super viewDidAppear:animated];     if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)])      {self.navigationController.interactivePopGestureRecognizer.delegate = self;    }}- (void)viewWillDisappear:(BOOL)animated {    [super viewWillDisappear:animated];    if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)])     {self.navigationController.interactivePopGestureRecognizer.delegate = nil;    }}- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{     return NO;}复制代码

UILabel设置内边距

子类化UILabel，重写drawTextInRect方法- (void)drawTextInRect:(CGRect)rect {    // 边距，上左下右    UIEdgeInsets insets = {0, 5, 0, 5};    [super drawTextInRect:UIEdgeInsetsInsetRect(rect, insets)];}复制代码

UILabel设置文字描边

子类化UILabel，重写drawTextInRect方法- (void)drawTextInRect:(CGRect)rect{    CGContextRef c = UIGraphicsGetCurrentContext();    // 设置描边宽度    CGContextSetLineWidth(c, 1);    CGContextSetLineJoin(c, kCGLineJoinRound);    CGContextSetTextDrawingMode(c, kCGTextStroke);    // 描边颜色    self.textColor = [UIColor redColor];    [super drawTextInRect:rect];    // 文本颜色    self.textColor = [UIColor yellowColor];    CGContextSetTextDrawingMode(c, kCGTextFill);    [super drawTextInRect:rect];}复制代码

UIView背景颜色渐变

+ (CAGradientLayer *)setGradualChangingColor:(UIView *)view fromColor:(NSString *)fromHexColorStr toColor:(NSString *)toHexColorStr{    //    CAGradientLayer类对其绘制渐变背景颜色、填充层的形状(包括圆角)    CAGradientLayer *gradientLayer = [CAGradientLayer layer];    gradientLayer.frame = view.bounds;    //  创建渐变色数组，需要转换为CGColor颜色    gradientLayer.colors = @[(__bridge id)[UIColor colorWithHexString:fromHexColorStr].CGColor,(__bridge id)[UIColor colorWithHexString:toHexColorStr].CGColor];    //  设置渐变颜色方向，左下点为(0,0), 右上点为(1,1)    gradientLayer.startPoint = CGPointMake(0, 0.5);    gradientLayer.endPoint = CGPointMake(1, 0.5);    //  设置颜色变化点，取值范围 0.0~1.0    gradientLayer.locations = @[@0,@1];        return gradientLayer;}复制代码

UIView某个角添加圆角

// 左上角和右下角添加圆角UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:(UIRectCornerTopLeft | UIRectCornerBottomRight) cornerRadii:CGSizeMake(20, 20)];CAShapeLayer *maskLayer = [CAShapeLayer layer];maskLayer.frame = view.bounds;maskLayer.path = maskPath.CGPath;view.layer.mask = maskLayer;复制代码

UIImage和base64互转

// view分类方法- (NSString *)encodeToBase64String:(UIImage *)image { return [UIImagePNGRepresentation(image) base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];}- (UIImage *)decodeBase64ToImage:(NSString *)strEncodeData {  NSData *data = [[NSData alloc]initWithBase64EncodedString:strEncodeData options:NSDataBase64DecodingIgnoreUnknownCharacters];  return [UIImage imageWithData:data];}复制代码

UIWebView设置背景透明

[webView setBackgroundColor:[UIColor clearColor]];[webView setOpaque:NO];复制代码

设置tableView分割线颜色以及顶到头

// 分割线颜色[self.tableView setSeparatorColor:[UIColor myColor]];// 顶到头- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {    [cell setSeparatorInset:UIEdgeInsetsZero];    [cell setLayoutMargins:UIEdgeInsetsZero];    cell.preservesSuperviewLayoutMargins = NO;}- (void)viewDidLayoutSubviews {    [self.tableView setSeparatorInset:UIEdgeInsetsZero];    [self.tableView setLayoutMargins:UIEdgeInsetsZero];}复制代码

为一个view添加虚线边框

CAShapeLayer *border = [CAShapeLayer layer]; border.strokeColor = [UIColor colorWithRed:67/255.0f green:37/255.0f blue:83/255.0f alpha:1].CGColor; border.fillColor = nil; border.lineDashPattern = @[@4, @2]; border.path = [UIBezierPath bezierPathWithRect:view.bounds].CGPath; border.frame = view.bounds; [view.layer addSublayer:border];复制代码

UITextView中打开或禁用复制，剪切，选择，全选等功能

// 继承UITextView重写这个方法- (BOOL)canPerformAction:(SEL)action withSender:(id)sender{// 返回NO为禁用，YES为开启    // 粘贴    if (action == @selector(paste:)) return NO;    // 剪切    if (action == @selector(cut:)) return NO;    // 复制    if (action == @selector(copy:)) return NO;    // 选择    if (action == @selector(select:)) return NO;    // 选中全部    if (action == @selector(selectAll:)) return NO;    // 删除    if (action == @selector(delete:)) return NO;    // 分享    if (action == @selector(share)) return NO;    return [super canPerformAction:action withSender:sender];}复制代码