Implement child UIView with fixed aspect ratio to aspect fit - ios

Question

I have some issue with autolayout.
We have ViewController with root view and child view.
Child view have fixed aspect ratio.
I need to fit child view in parent while rotation.
Also chid view should be centered.
Like on a picture:
I have this code:
- (void)viewDidLoad
{
[super viewDidLoad];
UIView * v = [UIView new];
v.backgroundColor = [UIColor redColor];
v.translatesAutoresizingMaskIntoConstraints = NO;
v.tag = 100;
[self.view addSubview:v];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|[v]|"
options:0
metrics:nil
views:#{#"v":v}]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|[v]|"
options:0
metrics:nil
views:#{#"v":v}]];
for (NSLayoutConstraint *c in self.view.constraints) {
[c setPriority:800];
}
NSLayoutConstraint *c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:v
attribute:NSLayoutAttributeWidth
multiplier:0.8
constant:0.];
[c setPriority:1000];
[v addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterY
multiplier:1
constant:0.];
[c setPriority:1000];
[self.view addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1
constant:0.];
[c setPriority:1000];
[self.view addConstraint:c];
}
And it's not working, it's shrinks outside superview in landscape.

Answer 1

I've made it work with the following constraints:
- (void)viewDidLoad
{
[super viewDidLoad];
UIView * v = [UIView new];
v.backgroundColor = [UIColor redColor];
v.translatesAutoresizingMaskIntoConstraints = NO;
v.tag = 100;
[self.view addSubview:v];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"H:|-(>=0)-[v]-(>=0)-|"
options:0
metrics:nil
views:#{#"v":v}]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:#"V:|-(>=0)-[v]-(>=0)-|"
options:0
metrics:nil
views:#{#"v":v}]];
NSLayoutConstraint *c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0];
[c setPriority:800];
[self.view addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0];
[c setPriority:800];
[self.view addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:v
attribute:NSLayoutAttributeWidth
multiplier:0.8
constant:0.];
[c setPriority:1000];
[v addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterY
multiplier:1
constant:0.];
[c setPriority:1000];
[self.view addConstraint:c];
c = [NSLayoutConstraint constraintWithItem:v
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1
constant:0.];
[c setPriority:1000];
[self.view addConstraint:c];
}
Screenshots: