UI控件（UIImageView）

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
   
    image1_ = [UIImage imageNamed:@"scene_in.jpg"];
    image2_ = [UIImage imageNamed:@"scene_out.jpg"];
    
    imageView_ = [[UIImageView alloc]initWithImage:image1_];
    [imageView_.image setAccessibilityIdentifier:@"image1"];
    imageView_.frame = CGRectMake(10, 20, 300, 200);
    
    //[imageView sizeToFit]; 设置视图与图片大小一致
    
    //设置图片为圆角
    imageView_.layer.masksToBounds = YES;
    imageView_.layer.cornerRadius = 5.0;
    
    //设置图片的透明度
    imageView_.alpha = 0.1;
    
    //是否隐藏该图像
    imageView_.hidden = NO;
    
    //增加点击响应事件
    imageView_.userInteractionEnabled = YES;
    UITapGestureRecognizer *singleTap =[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(onClickImage)];
    [imageView_ addGestureRecognizer:singleTap];
    
    [self.view addSubview:imageView_];
    
}

-(void)onClickImage{
    //切换图片显示
    NSLog(@"%@", imageView_.image.accessibilityIdentifier);
    if([imageView_.image.accessibilityIdentifier isEqualToString:@"image1"]){
        [imageView_ setImage:image2_];
        [imageView_.image setAccessibilityIdentifier:@"image2"];
    }else{
        [imageView_ setImage:image1_];
    }    
}

@end