create uibutton subclass - iphone

Question

I tried to subclass UIButton to include an activity indicator, but when i use initWithFrame:(since i'm subclassing uibutton i'm not using buttonWithType:) the button doesn't display. Also how would i set the button type in this case?:
my view controller:
ActivityIndicatorButton *button = [[ActivityIndicatorButton alloc] initWithFrame:CGRectMake(10, 10, 300, 44)];
[button addTarget:self action:#selector(buttonPressed) forControlEvents:UIControlEventTouchUpInside];
[button setTitle:#"Older Posts..." forState: UIControlStateNormal];
[cell addSubview:button];
[button release];
my activityindicatorbutton class:
#import <Foundation/Foundation.h>
#interface ActivityIndicatorButton : UIButton {
UIActivityIndicatorView *_activityView;
}
-(void)startAnimating;
-(void)stopAnimating;
#end
#implementation ActivityIndicatorButton
- (id)initWithFrame:(CGRect)frame {
if (self=[super initWithFrame:frame]) {
_activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
_activityView.frame = CGRectOffset(_activityView.frame, 60.0f, 10.0f);
[self addSubview: _activityView];
}
return self;
}
-(void) dealloc{
[super dealloc];
[_activityView release];
_activityView = nil;
}
-(void)startAnimating {
[_activityView startAnimating];
}
-(void)stopAnimating {
[_activityView stopAnimating];
}
#end

Answer 1

Favour composition over inheritance.
Create a UIView which contains the components you need and add them to your view.

Answer 2

I ran into a similar situation, and agree with Jeff that you don't really need to subclass UIButton. I solved this by subclassing UIControl, and then overriding layoutSubviews to do all of the configuration of the views I wanted on my "button". It's a much more simple implementation that subclassing UIButton since there does seem to be some hidden mojo going on under the hood. My implementation looked like this:
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.opaque = YES;
self.imageView = [[UIImageView alloc] initWithFrame:CGRectZero];
[self addSubview:self.imageView];
self.textLabel = [[UILabel alloc] initWithFrame:CGRectZero];
[self addSubview:self.textLabel];
}
return self;
}
And layoutSubviews looked like this:
- (void)layoutSubviews {
[super layoutSubviews];
// Get the size of the button
CGRect bounds = self.bounds;
// Configure the subviews of the "button"
...
}

Answer 3

I have created a custom class, preferring composition over inheritance and it works perfect. My custom class has a button and it knows it's MCContact object. Also it draws a proper button and calculates frames automatically using MCContact object, that is passed.
Header file sample:
#import <UIKit/UIKit.h>
#protocol MCContactViewDelegate;
#interface MCContactView : UIView
{
}
#property (nonatomic, strong) MCContact *mcContact;
#property (nonatomic, weak) id <MCContactViewDelegate> delegate;
- (id)initWithContact:(MCContact*)mcContact delegate:(id <MCContactViewDelegate>)delegate;
#end
#protocol MCContactViewDelegate <NSObject>
- (void)contactViewButtonClicked:(MCContactView*)contactView;
#end
Implementation file:
#import "MCContactView.h"
#interface MCContactView()
{
UIButton *_button;
}
#end
#implementation MCContactView
- (id)initWithContact:(MCContact*)mcContact delegate:(id <MCContactViewDelegate>)delegate
{
self = [super initWithFrame:CGRectZero];
if (self) {
GetTheme();
_mcContact = mcContact;
_delegate = delegate;
_button = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage *normalBackgroundImage = [[UIImage imageNamed:#"tokenNormal.png"] stretchableImageWithLeftCapWidth:12.5 topCapHeight:12.5];
[_button setBackgroundImage:normalBackgroundImage forState:UIControlStateNormal];
UIImage *highlightedBackgroundImage = [[UIImage imageNamed:#"tokenHighlighted.png"] stretchableImageWithLeftCapWidth:12.5 topCapHeight:12.5];
[_button setBackgroundImage:highlightedBackgroundImage forState:UIControlStateHighlighted];
_button.titleLabel.font = [theme contactButtonFont];
[_button setTitleColor:[theme contactButtonTextColor] forState:UIControlStateNormal];
[_button setTitleEdgeInsets:UIEdgeInsetsMake(4, 6, 4, 6)];
NSString *tokenString = ([allTrim(mcContact.name) length]>0) ? mcContact.name : mcContact.eMail;
[_button setTitle:tokenString forState:UIControlStateNormal];
[_button addTarget:self action:#selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
CGSize size = [tokenString sizeWithFont:[theme contactButtonFont]];
size.width += 20;
if (size.width > 200) {
size.width = 200;
}
size.height = normalBackgroundImage.size.height;
[_button setFrame:CGRectMake(0, 0, size.width, size.height)];
self.frame = _button.frame;
[self addSubview:_button];
}
return self;
}
- (void)buttonClicked:(id)sender
{
[self.delegate contactViewButtonClicked:self];
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
#end

Answer 4

You have a pretty obvious problem that concerns your dealloc method: [super dealloc]; must be called AT THE END of your implementation, or else the line after that will try to access a memory space (the ivar space) that has been already deallocated, so it's going to crash.
For the other problem, I'm not sure it's a good idea to put an activity monitor as the subview of a button in general...

Answer 5

You don’t really want to subclass UIButton. It’s a class cluster, so individual instances will be something like UIRoundRectButton or some other private Apple class. What are you trying to do that requires a subclass?