Question

If I have a superview.frame = CGRectMake(0,0,200,200); and a subview.frame = CGRectMake(0,0,100,100), subview has flexiable width and height, I think when superview’s frame changes to (0,0,150,150), then subview’s frame should change to (0, 0, 75, 75). But it’s not.

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

UIView * view1 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
view1.backgroundColor = [UIColor blackColor];
[self.view addSubview:view1];

UIView * view2 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
view2.backgroundColor = [UIColor redColor];
view2.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleTopMargin;
[view1 addSubview:view2];

view1.frame = CGRectMake(0, 0, 150, 150);
[self printRect:view2.frame];
}

- (void) printRect:(CGRect)rect
{
NSLog(@"%0.1f, %0.1f, %0.1f, %0.1f", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
}

Output:

0.0, 0.0, 50.0, 50.0

And when superview’s frame changes to (0,0,100,100), subview’s frame will become (0,0,0,0)

Why..

Answer 1

Replace your line of code with mine as u forgot UIViewAutoresizingFlexibleBottomMargin and UIViewAutoresizingFlexibleTopMargin

  view2.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleTopMargin;