创建 uibutton 子类

Question

我尝试子类化 UIButton 以包含活动指示器，但是当我使用 initWithFrame:(因为我是子类化 uibutton 我没有使用 buttonWithType:) 时，按钮不显示。另外在这种情况下我将如何设置按钮类型？：

我的视图控制器：

    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];

我的活动指示器按钮类：

#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

支持组合而不是继承。

创建一个 UIView ，其中包含您需要的组件并将它们添加到您的视图中。

Answer 2

我遇到了类似的情况，并且同意 Jeff 的观点，即您实际上不需要子类化 UIButton。我通过子类化 UIControl 解决了这个问题，然后覆盖 layoutSubviews 以在我的“按钮”上完成我想要的所有视图配置。这是一个比 UIButton 子类化的更简单的实现，因为引擎盖下似乎有一些隐藏的魔力。我的实现如下所示：

- (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;
}

layoutSubviews 看起来像这样：

- (void)layoutSubviews {
[super layoutSubviews];

// Get the size of the button
CGRect bounds = self.bounds;

// Configure the subviews of the "button"
...
}

Answer 3

我创建了一个自定义类，它更喜欢组合而不是继承，并且它工作得很好。我的自定义类有一个按钮，它知道它是 MCContact 对象。它还绘制了一个适当的按钮并使用传递的 MCContact 对象自动计算帧。

头文件示例：

#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

实施文件：

#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

您有一个与您的 dealloc 方法有关的非常明显的问题：[super dealloc];必须在实现的末尾调用，否则后面的行将尝试访问已被释放的内存空间（ivar 空间），因此它会崩溃。

对于另一个问题，我不确定将活动监视器作为一般按钮的子视图是否是个好主意...

Answer 5

你并不想继承UIButton。这是一个类集群，因此单个实​​例将类似于 UIRoundRectButton 或其他一些私有 Apple 类。你想做什么需要子类？