objective-c : 코드로 autolayout 추가하기

- (void)viewDidLoad {
     [super viewDidLoad];

     UIView *view = [UIView new];
     view.backgroundColor = [UIColor redColor];

     [view setTranslatesAutoresizingMaskIntoConstraints:NO];
     [self.view addSubview:view];
     
     NSLayoutConstraint *left = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeLeftrelatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeft multiplier:1 constant:100];

     NSLayoutConstraint *top = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1 constant:100];

     NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:50];

     NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:50];

     [self.view addConstraints:@[left, top]];
     [view addConstraints:@[height, width]];
}

width에 constant를 뷰의 넓이와 동일하게 한다면
CGRect rcData = [[UIScreen mainScreen] bounds];
     NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:rcData.size.width];