Question

我有一个基于UIButton的自定义类，我在这个自定义类中调用自定义setter方法时遇到了困难。我将在这些文件中列出代码：

CallMyMethod.h（UIButton的子类）
CallMyMethod.m
CallOtherClassMethod.h（在CallMyMethod中调用setter方法）
CallOtherClassMethod.m

CallMyMethod.h

@interface CallMyMethod : UIButton

@property (nonatomic, setter=setIsSelected:) BOOL isSelected;
@property (nonatomic, retain) UIImageView *checkmarkImageView;

- (void)setIsSelected:(BOOL)aIsSelected; //this is unnecessary, I guess

@end

CallMyMethod.m

@implementation CallMyMethod

@synthesize isSelected = _isSelected;
@synthesize checkmarkImageView = _checkmarkImageView;

- (id)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self) {
    // Initialization code
    [self loadView];
  }
  return self;
}

- (void) loadView
{
  [self.checkmarkImageView setHidden:YES];
}

- (UIImageView *)checkmarkImageView
{
    if (_checkmarkImageView == nil) {

      UIImage *checkmarkImage = [UIImage imageNamed:@"checkmark.png"];

      _checkmarkImageView = [[UIImageView alloc]initWithImage:checkmarkImage];

      [_checkmarkImageView setFrame:CGRectMake(10, 10, 32, 32)];

      [self addSubview:_checkmarkImageView];
  }

  return _checkmarkImageView;
}

- (void)setIsSelected:(BOOL)aIsSelected
{
  _isSelected = aIsSelected;

  [self.checkmarkImageView setHidden:!_isSelected];
  [self addSubview:_checkmarkImageView];

}

@end

CallOtherClassMethod.h

@class CallMyMethod;    

@interface CallOtherClassMethod : UIViewController

@property (nonatomic,retain) CallMyMethod *btnCMM;

@end

CallOtherClassMethod.m

#import "CallMyMethod.h"

@implementation CallOtherClassMethod

@synthesize btnCMM;

- (void)viewDidLoad
{
  [super viewDidLoad];
  self.btnCMM = [[CallMyMethod alloc]initWithFrame:CGRectMake(0, 30, 50, 70)];

  //somewhere in my code I will add btnCMM to the view
  [someView bringSubviewToFront: btnCMM];
  [someView addSubview: btnCMM];

}

//somewhere where I pressed a button to trigger this method
- (IBAction) pressMe:(id)sender
{
  NSLog(@"self.btnCMM %@", self.btnCMM); //returned as btnCMM is nil ?!
  [self.btnCMM setIsSelected:YES];
}

@end

问题在于程序无法在setIsSelected方法中运行代码，我已经在NSLog中跟踪btnCMM为nil。我想知道为什么会这样，因为当我将CallOtherClassMethod称为UIViewController时，viewDidLoad会初始化我的自定义按钮。我在这里做错了吗？

Answer 1

为什么不覆盖setSelected，这是UIButton上的一个方法，然后使用button.selected = YES？

如果你想调试你的按钮变为零的原因，在你的UIButton子类中实现dealloc，在那里放一个断点，并查看堆栈跟踪以找到原因。

自定义UIButton的setIsSelected方法未被称为

1 个答案: