IPhone button sizing

Question

Does anyone know how to control the size of navigation bar buttons?
I'm creating a button with the pen-and-paper image UIImageNameMessageCompose. (Thanks Chippydip, for telling me about these system image constants.) Here's the code I used (pretend the curly braces are square):
button = {UIButton buttonWithType:UIButtonTypeNavigation};
{button setImage:{UIImage imageNamed:UIImageNameMessageCompose} forStates:...};
The problem is, instead of a pretty square-ish button like you see in the Mail and Text apps on the iPhone, I get a huge ugly wide button. There seems to be a minimum margin imposed around the image. Also, the image is not centered vertically in the button.
Changing the frame size of the button has no effect. I see there are properties of buttons called "contentInset" and "imageInset" but I'm not sure what these do. Does anyone know how to make my button look like the ones in Mail and Text?
Thanks,
Eliza

Answer 1

I've solved the problem. It's a matter of just setting the button's frame by hand. When I thought that wouldn't work before, it was because I was first setting the frame, then setting the image. When you set the button image it re-sets the frame to be 20 pts wider than the image.
So you just have to set the image first, then set the frame.
For those interested, the following code makes a nice square-ish "compose message" button in the nav bar (the content edge inset fix centers the image vertically):
UIButton *button = {UIButton buttonWithType:UIButtonTypeNavigation};
{button setImage:{UIImage imageNamed:UIImageNameMessageCompose forStates:UIControlStateNormal};
button.contentEdgeInsets = UIEdgeInsetsMake(-2, 0, 2, 0);
button.frame = CGRectMake(0, 0, 35, 30);
-eliza