爲什麼我無法更新我的UIImageView？

Question

我做我自己的UIImageView，像這樣：

@interface MyImageView : UIImageView{ 


} 

和我有initWithFrame這樣的：

- (id)initWithFrame{ 
    if((self = [ super initWithFrame: CGRectMake(0, 0, 175, 175) ])) { 

    UIImage *img = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"myImage" ofType:@"png"]]; 
    CGRect cropRect = CGRectMake(175, 0, 175, 175); 
    CGImageRef imageRef = CGImageCreateWithImageInRect([img CGImage], cropRect); 
    //self = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 175, 175)]; 
    //self.image = [UIImage imageWithCGImage:imageRef]; 
    [self setImage:[UIImage imageWithCGImage:imageRef]]; 


    CGImageRelease(imageRef); 
    } 
    return self; 

} 

我想改變，當用戶touchesBegin的形象，所以我有這樣的事情：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 

    UIImage *img = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"myImage2" ofType:@"png"]]; 
    CGRect cropRect = CGRectMake(0, 0, 175, 175); 
    CGImageRef imageRef = CGImageCreateWithImageInRect([img CGImage], cropRect); 
    //self = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 175, 175)]; 
    [self setImage:[UIImage imageWithCGImage:imageRef]]; 
    CGImageRelease(imageRef); 
} 

我發現我無法更改圖像。所以，我添加了一行[self addSubview：imageView];在touchesBegan方法中，這是工作。但我不知道爲什麼我無法改變touchesBegan的形象，thz。

Answer 1

爲什麼要返回void從initWithFrame ??

您應該從initWithFrame返回初始化對象。

- (id)initWithFrame{  
    if((self = [ super initWithFrame: CGRectMake(0, 0, 175, 175) ])) { 
     UIImage *img = [UIImage imageWithContentsOfFile: [[NSBundle mainBundle]  pathForResource:@"myImage" ofType:@"png"]]; 
     CGRect cropRect = CGRectMake(175, 0, 175, 175); 
     CGImageRef imageRef = CGImageCreateWithImageInRect([img CGImage], cropRect); 
     self.image = [UIImage imageWithCGImage:imageRef]; 
     [self addSubview:imageView]; 
     CGImageRelease(imageRef); 
    } 
    return self; 
}