创建具有删除功能的自定义 UIButton 类

Question

我有一个 UIButton 网格。当我点击“编辑”按钮时，我希望在每个按钮上出现一个删除按钮，按下该按钮会删除按钮（和相关数据）。有点像苹果的主屏幕，当你按住一个按钮时，它开始摆动，角落里有一个 X。

根据这篇文章：Subclass UIButton to add a property 我可以使用关联引用为我的每个按钮添加一个属性。我试图添加一个 UIButton 作为我的自定义 UIButton 的属性，但我似乎无法让它出现并且感觉这不是正确的方法。这是我的自定义主按钮：

    #import "UIButton+Property.h"
#import <objc/runtime.h>

@implementation UIButton(Property)

static char UIB_DELETEBUTTON_KEY;

@dynamic deleteButton;


- (void)setDeleteButton:(UIButton *)deleteButton {
    deleteButton = [UIButton buttonWithType:UIButtonTypeInfoDark];
    deleteButton.frame = CGRectMake(100, 100, 50, 50);
    objc_setAssociatedObject(self, &UIB_DELETEBUTTON_KEY, deleteButton, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (UIButton *)deleteButton {
    return (UIButton *)objc_getAssociatedObject(self, &UIB_DELETEBUTTON_KEY);
}

@end

这是我以编程方式添加按钮的地方：

//Create a custom button for each custom book doc
for (int i = 0; i < [customBookDocs count]; ++i) {
    BookDoc *customBookDoc = [customBookDocs objectAtIndex:i];
    NSString *bookTitle = customBookDoc.book.title;

    //create a button for each book
    CGRect frame = CGRectMake(xCoord, yCoord, 200, 200);
    UIButton *bookButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    bookButton.bookDoc = customBookDoc;
    [bookButton setFrame:frame];
    [bookButton setTitle:bookTitle forState:UIControlStateNormal];
    [bookButton addTarget:self action:@selector(bookButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    xCoord += 250;

    [self.view addSubview:bookButton];
    [self.view addSubview:bookButton.deleteButton];
}

有没有更简单、更明智的方法来做到这一点？还是我走在正确的轨道上？

Answer 1

原始回复开始：

...其他人可能对此有更多话要说，但我不确定您为什么需要在这里使用对象关联。您当然可以使用常规子类化将另一个按钮作为属性添加到您的按钮，这是我将采取的路线。 ...

以下编辑：

我以为我直接继承了一个UI控件，但是我去寻找代码的时候发现我错了。 @Joe 在 cmets 中正确指出直接子类化 UI 控件存在问题。

通过创建一个包装类来保存按钮及其相关的删除按钮，我能够在不使用关联对象的情况下实现类似于您描述的功能。它可以工作，但不是很灵活，所以我一般会推荐@Joe 的方法作为更好的解决方案。

以下是相关代码：

为了简单起见，我将所有代码都放入了 appDelegate。我不建议在现实生活中这样做。

AppDelegate.m：

@implementation AppDelegate

@synthesize window = _window;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    self.window.backgroundColor = [UIColor whiteColor];

    UIButton *toggleDeleteButtons = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [toggleDeleteButtons setFrame:CGRectMake(20, 45, 280, 45)];
    [toggleDeleteButtons setTitle:@"Toggle Delete" forState:UIControlStateNormal];
    [toggleDeleteButtons addTarget:self action:@selector(toggleDeleteButtonAction) forControlEvents:UIControlEventTouchUpInside];
    [[self window] addSubview:toggleDeleteButtons];

    ButtonWrapper *myButtonWrapper = [[ButtonWrapper alloc] init];
    [[myButtonWrapper button] setFrame:CGRectMake(20, 100, 200, 45)];
    [[myButtonWrapper button] setTitle:@"This is my button" forState:UIControlStateNormal];
    [[myButtonWrapper deleteButton] addTarget:self action:@selector(buttonDeleteRequested:) forControlEvents:UIControlEventTouchUpInside];
    [[myButtonWrapper deleteButton] setTag:0];
    [[self window] addSubview:[myButtonWrapper button]];
    buttonWrapper1 = myButtonWrapper;

    // Added instance called anotherButtonWrapper with tag 1, as above

    // Added instance called stillAnotherButtonWrapper with tag 2, as above

    [self.window makeKeyAndVisible];
    return YES;
}

- (void)toggleDeleteButtonAction {
    static BOOL deleteButtonsShown;

    [buttonWrapper1 showDeleteButton:!deleteButtonsShown];
    [buttonWrapper2 showDeleteButton:!deleteButtonsShown];
    [buttonWrapper3 showDeleteButton:!deleteButtonsShown];
    deleteButtonsShown = !deleteButtonsShown;
}

- (void)buttonDeleteRequested:(UIButton *)deleteButton {
    // delete the specified button here
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Delete" message:[NSString stringWithFormat:@"Delete was pressed on button %i",[deleteButton tag]]delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
}

ButtonWrapper.m：

@implementation ButtonWrapper

@synthesize button;
@synthesize deleteButton;

- (ButtonWrapper *)init {
    ButtonWrapper *newWrapper = [ButtonWrapper alloc];

    UIButton *myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [myButton setFrame:CGRectZero];

    UIButton *myDeleteButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [myDeleteButton setFrame:CGRectMake(0, 0, 100, 40)];
    [myDeleteButton setTitle:@"Delete" forState:UIControlStateNormal];
    [myDeleteButton setHidden:TRUE];
    [myButton addSubview:myDeleteButton];

    [newWrapper setButton:myButton];
    [newWrapper setDeleteButton:myDeleteButton];

    return newWrapper;
}

- (void)showDeleteButton:(BOOL)showButton {
    if (showButton) {
        [[self deleteButton] setHidden:FALSE];
        [[self deleteButton] setEnabled:TRUE];    }
    else {
        [[self deleteButton] setHidden:TRUE];
        [[self deleteButton] setEnabled:FALSE];
    }
}
@end

这个解决方案不需要我实现所有的 UI 属性，但它确实需要额外的工作来连接嵌入式委托，这很麻烦。可能有一种方法可以在初始化时将委托传递给包装器，但我无法使其工作。