Add UIImageView inside UIView at exactly centre of the view

Question

I add UIView which has the size equal to screen size than I add UIImageView to this view. I want to set this UIImageView at exactly centre of the UIView . I'm doing this programatically therefore, can't put constraints via storyboard. Below is my code:

UIView* viewForImage = [[UIView alloc] initWithFrame:screenRect];
CGRect rect = CGRectMake(0, 0, 100, 200);
UIImageView* imgcoverView = [[UIImageView alloc] initWithFrame:rect];
imgcoverView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.9];
imgcoverView.image = imgView.image;
[viewForImage addSubview:imgcoverView];

Answer 1

imgcoverView.center = CGPointMake(viewForImage.frame.size.width/2,viewForImage.frame.size.height/2) ;

Answer 2

Please consider different orientation of the device. I think it's better to add as two centre constraints.

NSLayoutConstraint *xCenterConstraint = [NSLayoutConstraint constraintWithItem:imgcoverView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:viewForImage attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0];
[viewForImage addConstraint:xCenterConstraint];

NSLayoutConstraint *yCenterConstraint = [NSLayoutConstraint constraintWithItem:imgcoverView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:viewForImage attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0];
[viewForImage addConstraint:yCenterConstraint];

Answer 3

You can Do it By constraint !!!

set only two Constraint Horizontal center in container and Vertical center in container

Answer 4

imgcoverView.frame = 
           CGRectMake(viewForImage.frame.origin.x + (viewForImage.frame.size.width - imgcoverView.frame.size.width)/2, 
                      viewForImage.frame.origin.y + (viewForImage.frame.size.height - imgcoverView.frame.size.height)/2,
                      imgcoverView.frame.size.width,
                      imgcoverView.frame.size.height);