廢話不多說直接上代碼，需要的自取
獲取緩存大小：

-(void)getCacheSize{
//得到緩存路徑
    NSString * path = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;
    NSFileManager * manager = [NSFileManager defaultManager];
    CGFloat size = 0;
//首先判斷是否存在緩存文件
    if ([manager fileExistsAtPath:path]) {
        NSArray * childFile = [manager subpathsAtPath:path];
        for (NSString * fileName in childFile) {
            //緩存文件絕對路徑
            NSString * absolutPath = [path stringByAppendingPathComponent:fileName];
            size = size + [manager attributesOfItemAtPath:absolutPath error:nil].fileSize;
        }
        //計算sdwebimage的緩存和系統(tǒng)緩存總和
        size = size + [[SDWebImageManager sharedManager].imageCache getSize];
    }
    size = [NSString stringWithFormat:@"%.2fM",size / 1024 / 1024];
}

刪除緩存：

-(void)cleanCache{
//獲取緩存路徑
    NSString * path = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES).lastObject;
    NSFileManager * manager = [NSFileManager defaultManager];
//判斷是否存在緩存文件
    if ([manager fileExistsAtPath:path]) {
        NSArray * childFile = [manager subpathsAtPath:path];
//逐個刪除緩存文件
        for (NSString *fileName in childFile) {
            NSString * absolutPat = [path stringByAppendingPathComponent:fileName];
            [manager removeItemAtPath:absolutPat error:nil];
        }
//刪除sdwebimage的緩存
        [[SDWebImageManager sharedManager].imageCache clearMemory];
    }
//這里是又調(diào)用了得到緩存文件大小的方法，是因為不確定是否刪除了所有的緩存，所以要計算一遍，展示出來
    [self getCacheSize];
}