iOS - Sub classed UIButton - Where to add code for highlighted state? - iphone

Question

I want to have my buttons in my iOS app to have a red gradient. At first I was using images to do this, but then realised I can do it with QuartzCore framework. I have the following implementation file:
#import "RedButton.h"
#implementation RedButton
#synthesize gradientLayer = _gradientLAyer;
- (void)awakeFromNib;
{
// Initialize the gradient layer
self.gradientLayer = [[CAGradientLayer alloc] init];
// Set its bounds to be the same of its parent
[self.gradientLayer setBounds:[self bounds]];
// Center the layer inside the parent layer
[self.gradientLayer setPosition:
CGPointMake([self bounds].size.width/2,
[self bounds].size.height/2)];
// Insert the layer at position zero to make sure the
// text of the button is not obscured
[[self layer] insertSublayer:self.gradientLayer atIndex:0];
// Set the layer's corner radius
[[self layer] setCornerRadius:5.0f];
// Turn on masking
[[self layer] setMasksToBounds:YES];
// Display a border around the button
// with a 1.0 pixel width
[[self layer] setBorderColor:[UIColor colorWithRed:(158.0f/255.0f) green:0.0f blue:0.0f alpha:1.0f].CGColor];
[[self layer] setBorderWidth:1.0f];
[self.gradientLayer setColors:[NSArray arrayWithObjects:
(id)[[UIColor colorWithRed:(214.0f/255.0f) green:0.0f blue:0.0f alpha:1.0f] CGColor],
(id)[[UIColor colorWithRed:(141.0f/255.0f) green:0.0f blue:0.0f alpha:1.0f] CGColor], nil]];
[[self layer] setNeedsDisplay];
}
- (void)drawRect:(CGRect)rect;
{
[super drawRect:rect];
}
- (void)dealloc {
// Release our gradient layer
self.gradientLayer = nil;
[super dealloc];
}
#end
First question - am I right to use awakeFromNib here? Or should I be using initWithFrame?
Second question - originally I was using images and using interface builder to set the default and highlighted states of the button. Now that I'm not using images, how can I set the appearance of the button to change when it's highlighted? I just want to reverse the gradient.
Third question - I've seen it written in some places that you shouldn't subclass UIButton. If not, how would I change all my buttons to have this gradient without duplicating a lot of code?
Thanks in advance.

Answer 1

edit1: Misread the part about images.
You should be able to do something like this to set the button states natively as image using your gradients
// your code for setting up the gradient layer comes first
UIGraphicsBeginImageContext(CGSizeMake(1, [self bounds].size.height));
[gradientLayer renderInContext: UIGraphicsGetCurrentContext()];
UIImage *bgImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self setBackGroundImage:bgImage forState:UIControlStateWhatever] // replace with correct states
============================
I recommend putting your initialization code in a function other than awakeFromNib (for the case where the button is actually NOT being used in a nib but possibly being created in code). You should create a custom initialization function and call it in both initWithCoder and initWithFrame This answer shows a pretty good pattern for doing so.
You can set the background for different states in your initialization by calling
[self setBackGroundImage: forState];
Where in this case your state would be UIControlStateHighlighted.
That aside, one argument against subclassing in this situation is that you're not actually defining any custom behavior, you're just trying to reuse some styling code. A subclass isn't necessary here and you can do something as simple as creating a formatting function somewhere (in your viewcontroller maybe, or some function in another class) that takes a UIButton as a scenario and performs all of that initialization code on it. This way, you will not have your buttons locked up in a subclass (which is useful if you actually end up using another UIButton subclass.. I for example like to use one that defines custom touch behavior allowing the button to be a non-rectangular shape (and have its touch area limited as such).
Another argument I've seen is that UIButton contains some factory functions that may return a button of a different type than your subclass, but you may never run into this issue if you don't use those functions.