其實很簡單，用的就是UITapGestureRecognizer，但是UIImageView的userInteractionEnabled屬性預設是NO，對，你沒看錯，NO！！！

所以要把這個引數設定成YES。親測管用，上程式碼：

    UIImage *img = [UIImage imageWithContentsOfFile:@"/Users/jinhui005/Desktop/style_img.png"];
    UIImageView *imgView = [[UIImageView alloc] initWithImage:img];
    UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickImage)];
    [imgView addGestureRecognizer:tapGesture];
    imgView.userInteractionEnabled = YES;