ios - UIImageView 位于顶部并设置大小

Question

1)我有一个UIView，上面有一个UIImageView，我从图片库加载图片。我想知道如何将图片“居中”在屏幕上并使纵横比不改变。例如，如果我加载横向模式的图片，如何确保图片不会拉伸(stretch)到整个屏幕？我的应用程序正在纵向模式下运行。

2)在同一个 View 中，我想添加这样的效果:当用户触摸屏幕时，按钮菜单会淡出，并在他再次按下时重新显示。我不确定它叫什么，而且我无法让点击手势识别器工作。

编辑:

我在页面加载时设置了UIImageView

- (void)viewDidLoad
{
[super viewDidLoad];
xlabel = [[UILabel alloc] initWithFrame:self.setLablePosition];
xlabel.backgroundColor = [UIColor clearColor];

imgView.image = self.appDelegate.theImg; // now the image is put on a UIImageView that is "full screen"
xlabel.text = @"Some text";
[imgView addSubview:xlabel];
// Do any additional setup after loading the view.
}

至于点击手势:

-(IBAction)screenTapped{
NSLog(@"screen Tapped");
}

IBAction 链接到点击手势识别器。

Answer 1

为了使 UIImageView 在 View 中居中，您需要执行以下操作

//First give imgView the correct size
//You may need to divide the size by some constant if the image is too big
imgView.frame = CGRectMake(0, 0, self.appDelegate.theImg.size.width, self.appDelegate.theImg.size.width);
//Then center it
imgView.center = self.view.center;

要添加点击手势识别器，请执行以下操作

UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(screenTapped)];
//By deafualt interaction is disabled
imgView.userInteractionEnabled = YES;
[imgView addGestureRecognizer:recognizer];