iOS View gets reset on addSubview

问题

I have a storyboard with a square imageView in the middle at: 280,140 (vertical) When the application starts i am able to move this imageView by pressing buttons. I move the imageView using:

    _mainImage.frame = CGRectMake(_mainImage.frame.origin.x + 2, _mainImage.frame.origin.y, _mainImage.frame.size.width, _mainImage.frame.size.height);

while the application is running i keep adding new imageViews to the mainView:

UIImageView *imgView;
imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, yCoordinate, 50, 10)];
imgView.backgroundColor = [UIColor whiteColor];
[self.view addSubview:imgView];

each time i call this code the square imageView i have placed in the middle and moved around, gets set back to its starting position. It seems like the mainView gets "reset" each time the addSubview gets called. Is there any way i can add a subview without having the mainView "reset"?

回答1:

Most likely your view is set up using Autolayout (this is the default for storyboards or nibs) and when you add a new subview, a layout pass is performed which resets your views position back to that defined by its original constraints.

You should move your view by updating its constraints, or turn off Autolayout. There are lots of posts around explaining how to do either of these things.

来源：https://stackoverflow.com/questions/22804966/ios-view-gets-reset-on-addsubview