如何从'sender'对象访问用户定义的运行时属性？

问题描述

我在Storyboard场景中有一个 UIButton 。该按钮配置了User-Defined-RunTime-Attribute'type'（String）。当按下按钮调用

I have a UIButton in a Storyboard scene. The button has a User-Defined-RunTime-Attribute 'type'(String) configured. When pressed the button calls

- （IBAction）pressedButton：（id）sender

我是否可以从'sender'访问User-Defined-RunTime-Attribute？

Will I be able to access the User-Defined-RunTime-Attribute from 'sender'?

推荐答案

是：

-(IBAction)pressedButton:(id)sender
{
    id value = [sender valueForKey:key];
}

---

请注意，您不能使用用户定义的运行时属性，除非您将UIButton子类化并将其添加为强属性，例如

@interface UINamedButton : UIButton
@property (strong) NSString *keyName;
@end

如果您设置了用户定义的运行时间属性，但尚未完成不幸的是，Xcode会严重崩溃。

If you set a User Defined Run Time attribute, and you have not done this, Xcode will badly crash unfortunately.

然后你可以得到这样的价值，如

You can then get that value like

-(IBAction)clicked:(UIControl *)sender
    {
    NSString *test = @"???";

    if ( [sender respondsToSelector:@selector(keyName)] )
            test = [sender valueForKey:@"keyName"];

    NSLog(@"the value of keyName is ... %@", test);

    // if you FORGOT TO SET the keyName value in storyboard, that will be NULL
    // if it's NOT a UINamedButton button, you'll get the "???"

    // and for example...
    [self performSegueWithIdentifier:@"idUber" sender:sender];
    // ...the prepareForSegue could then use that value in the button.

    // note that a useful alternative to
    // if ( [sender respondsToSelector:@selector(stringTag)] )
    // is... 
    // if ( [sender respondsToSelector:NSSelectorFromString(@"stringTag")] )
    }

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