如何在屏幕上显示 UIControl 的子类 [英] How to display a Subclass of UIControl on the screen

问题描述

我通过以下代码创建了一个名为 ToggleImageControl 的 UIControl 子类(参考以下帖子 UITableViewCell 中的复选框图像切换)

I have created a subclass of UIControl called ToggleImageControl via the following code (with reference to the following post Checkbox image toggle in UITableViewCell)

@interface ToggleImageControl : UIControl 
{
    BOOL photoIsStarred;
    UIImageView *imageView;
    UIImage *normalImage;
    UIImage *selectedImage;
}

@property (nonatomic, assign) BOOL photoIsStarred;
@property (nonatomic, retain) UIImageView *imageView;
@property (nonatomic, retain) UIImage *normalImage;
@property (nonatomic, retain) UIImage *selectedImage;

- (void) toggleImage;
@end


@implementation ToggleImageControl

@synthesize photoIsStarred, imageView, normalImage,selectedImage;

- (id)initWithFrame:(CGRect)frame 
{
    NSLog(@"in inti with frame method");
    self.normalImage = [UIImage imageNamed: @"blank_star.png"];
    self.selectedImage = [UIImage imageNamed: @"star.png"];
    self.imageView = [[UIImageView alloc] initWithImage: normalImage];

    // set imageView frame
    [self addSubview: imageView];

    [self addTarget: self action: @selector(toggleImage) forControlEvents: UIControlEventTouchDown];

return self;
}

- (void) toggleImage
{
    NSLog(@"image toggled");
    self.photoIsStarred = !photoIsStarred;
    self.imageView.image = (photoIsStarred ? selectedImage : normalImage); 
}

@end

我尝试在表格单元格中创建 ToggleImageControl 的实例，但无法显示正常图像".下面我的实现中是否遗漏了什么?

I tried to create an instance of ToggleImageControl in a table cell but was not able to display the 'normal image'. Is there something missing from my implementation below?

//In a UItableview cell
ToggleImageControl *toggleControl = [[ToggleImageControl alloc]initWithFrame:CGRectMake(670, 10,80, 80)];

[cell.contentView addSubview:toggleControl];

推荐答案

确保在您的 initWithFrame: 方法中调用 [super initWithFrame:frame].

Make sure to call [super initWithFrame:frame] in your initWithFrame: method.

例如

self = [super initWithFrame:frame];
if (self) {

  // Initialization

}

return self;

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