- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 44, 44)];    imageView.image=[self defaultImage];    [self.view addSubview:imageView];    }-(UIImage *)defaultImage {    static UIImage *defaultImage = nil;    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        UIGraphicsBeginImageContextWithOptions(CGSizeMake(20.f, 13.f), NO, 0.0f);                [[UIColor blackColor] setFill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, 20, 1)] fill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 5, 20, 1)] fill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 10, 20, 1)] fill];                [[UIColor whiteColor] setFill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 1, 20, 2)] fill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 6,  20, 2)] fill];        [[UIBezierPath bezierPathWithRect:CGRectMake(0, 11, 20, 2)] fill];                defaultImage = UIGraphicsGetImageFromCurrentImageContext();        UIGraphicsEndImageContext();            });    return defaultImage;}