如何在 Objective-C 中使用自定义委托 [英] How to use custom delegates in Objective-C

问题描述

我需要了解Objective-C中委托方法的使用.谁能指出我正确的来源?

I need to know about the usage of delegate methods in Objective-C. Can anyone point me to the correct source?

推荐答案

你需要为你的类声明一个委托协议.类 Foo 的委托协议和接口的示例可能如下所示:

You will want to declare a delegate protocol for your class. An example of a delegate protocol and interface for class Foo might look like this:

@class Foo;
@protocol FooDelegate <NSObject>
@optional
- (BOOL)foo:(Foo *)foo willDoSomethingAnimated:(BOOL)flag;
- (void)foo:(Foo *)foo didDoSomethingAnimated:(BOOL)flag;
@end

@interface Foo : NSObject {
     NSString *bar;
     id <FooDelegate> delegate;
}

@property (nonatomic, retain) NSString *bar;
@property (nonatomic, assign) id <FooDelegate> delegate;

- (void)someAction;

@end

不要忘记在 @implementation 中综合你的属性.

Don't forget to synthesize your properties in the @implementation.

这段代码所做的是声明一个名为 FooDelegate 的协议；符合此协议的类将被声明为 @interface SomeClass : SuperClass ;{}.因为这个类符合协议 FooDelegate，它现在可以实现 FooDelegate 下的方法(要求实现这些方法，使用 @required而不是 @optional).最后一步是在符合FooDelegate的类中实例化一个Foo对象，并让这个Foo对象拥有它的delegate属性设置:

What this code did was declare a protocol called FooDelegate; a class that conforms to this protocol would be declared like @interface SomeClass : SuperClass <FooDelegate> {}. Because this class conforms to the protocol FooDelegate, it now gets to implement the methods under FooDelegate (to require that these be implemented, use @required instead of @optional). The last step is for a Foo object to be instantiated in the class that conforms to FooDelegate, and for this Foo object to have its delegate property set:

Foo *obj = [[Foo alloc] init];
[obj setDelegate:self];

现在，您的类已准备好接收来自 Foo 对象的消息，这些对象的委托设置正确.

Now, your class is prepared to receive messages from Foo objects that have their delegates set correctly.

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