如何设置UIImageView的特定大小

Question

I got a weird bug going on. I'm trying to programatically initialize an UIImageView with a specific frame and image. My image is 60x60, but I'm trying to resize it to 30x30 on the screen, which seems impossible.

The following works, but show the image in 60x60:

 UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"logo.png"]];
    [imgView setContentMode:UIViewContentModeScaleAspectFit];
//    imgView.frame = CGRectMake(100, 200, 30, 30);
    imgView.center = CGPointMake(pointTouch.x, pointTouch.y);
    [self.view addSubview:imgView];

And the following just doesn't show anything at all on the screen:

  UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"logo.png"]];
    [imgView setContentMode:UIViewContentModeScaleAspectFit];
    imgView.frame = CGRectMake(100, 200, 30, 30);
    imgView.center = CGPointMake(pointTouch.x, pointTouch.y);
    [self.view addSubview:imgView];

What's wrong?

EDIT : for those having the same problem, here is the working code:

UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"logo.png"]];
imgView.frame = CGRectMake(self.view.bounds.size.width/2, self.view.bounds.size.height/2, 30, 30);
imgView.center = CGPointMake(pointTouch.x, pointTouch.y);
[imgView setContentMode:UIViewContentModeScaleAspectFill];
[self.view addSubview:imgView];

Answer 1

Start experiment with

imgView.center = CGPointMake(view.bounds.x/2, view.bounds.y/2);
imgView.bounds = view.bounds; 

and see if this fills the superview. Then try CGPointMake(pointTouch.x, pointTouch.y) and CGPointMake(30,30) respectively.

I'm guessing this behaviour has something to do with warning about frame :

If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.

Answer 2

You could try initializing the UIImageView with a set frame, then setting the image after that:

UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 200, 30, 30)];
[imgView setContentMode:UIViewContentModeScaleAspectFit];
imgView.image = [UIImage imageNamed:@"logo.png"];
imgView.center = CGPointMake(pointTouch.x, pointTouch.y);
[self.view addSubview:imgView];