titleEdgeInsets for UIButton make no sense - ios

Question

I have an image and a title for a UIButton. I'm trying to get my image (15px in width) to be aligned left and my title to be aligned 5px left of that:
The button is 215 in width, but I had to set my titleEdgeInset right to -44. This doesn't make sense. What are the maths to get -44?

Answer 1

It's because the image and title of a button are centered together by default.
For example, here's a 300px wide button with an image and text, no insets:
Looks like I need the button contents shifted left by 60 pts, so -60 left inset and 60 right inset.
button.imageEdgeInsets = UIEdgeInsetsMake(0.0, -60.0, 0.0, 60.0)
button.titleEdgeInsets = UIEdgeInsetsMake(0.0, -60.0, 0.0, 60.0)
Edit:
These insets would also work for the above example.
button.imageEdgeInsets = UIEdgeInsetsMake(0.0, -120.0, 0.0, 0.0)
button.titleEdgeInsets = UIEdgeInsetsMake(0.0, -120.0, 0.0, 0.0)
The button is centering its contents, so if you say "there are 2 more pts on the left" the button will move its contents over by 1 pt to keep them centered.
The rule is
-leftInset+rightInset=leftMargin*2

Answer 2

UIButton is centered by default like the other answers stated, but you can change that to achieve a more intuitive inset behaviour.
Select left alignment in the attributes inspector.
Then set insets like this:
button.imageEdgeInsets = UIEdgeInsets.zero
button.titleEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 0)

Answer 3

It's easy to do:
In swift:
let button: UIButton = UIButton(frame: CGRect(x: 44, y: 64, width: 100, height: 40))
button.backgroundColor = UIColor.clear
button.setImage(UIImage(named: "img"), for: .normal)
button.setTitle("hello", for: .normal)
button.layer.borderWidth = 1
button.layer.borderColor = UIColor.blue.cgColor
button.layer.cornerRadius = 4
// set edge inset
button.imageEdgeInsets = UIEdgeInsets(top: 0, left: -40, bottom: 0, right: 0)
button.titleEdgeInsets = UIEdgeInsets(top: 0, left: -20, bottom: 0, right: 0)
view.addSubview(button)
In objective-c:
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(44, 64, 100, 40);
button.backgroundColor = [UIColor clearColor];
[button setImage:[UIImage imageNamed:#"img"] forState:UIControlStateNormal];
[button setTitle:#"hello" forState:UIControlStateNormal];
[button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
button.layer.cornerRadius = 4;
button.layer.borderColor = [UIColor blueColor].CGColor;
button.layer.borderWidth = 1;
// set edge inset
button.imageEdgeInsets = UIEdgeInsetsMake(0, -40, 0, 0);
button.titleEdgeInsets = UIEdgeInsetsMake(0, -20, 0, 0);
[self.view addSubview:button];
[![The result][1]][1]
[1]: https://i.stack.imgur.com/FyzqB.png