Xcode Label not centered

Question

Programmatically created a scroll view then added a label.

scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0,self.view.frame.size.width, self.view.frame.size.height)];

[self.view addSubview:scrollView];

then label

UILabel *errLabel = [[UILabel alloc] init];
errLabel.text = @"Top Label";
//errLabel.frame = CGRectMake(self.view.frame.size.width/2,50,120,20);
errLabel.frame = CGRectMake(CGRectGetWidth(scrollView.frame)/2.00,50,120,20);
errLabel.textAlignment = NSTextAlignmentCenter;
errLabel.layer.borderColor = [UIColor grayColor].CGColor;
errLabel.layer.borderWidth = 3.0;
[errLabel setFont:[UIFont fontWithName:@"Helvetica-Bold" size:14]];
[scrollView addSubview:errLabel];

In the simulator for iPhone 8, 11 Pro Max, and biggest iPad the label is right of center. Is this an iOS 11 bug or am I missing something?

Answer 1

This is because the way you are creating the frame for your label, you are starting the frame at the mid point of the scroll view.

This will offset the starting X point to center your label:

errLabel.frame = CGRectMake(CGRectGetWidth(scrollView.frame)/2.00 - 60,50,120,20)