使用标量参数调用选择器 [英] Invoke selector with scalar argument

问题描述

我目前使用 objc_msgSend 在对象集合上调用这样的选择器.有没有更好的方法来做到这一点?这是我的代码:

I currently use objc_msgSend to invoke such selector on collection of object. Is there any better way to do that? Here is my code:

@protocol ADelegateProtocol {
   -(void) timeToEventOneDidChange:(NSInterval) event1;
   -(void) timeToEventTwoDidChange:(NSInterval) event1;
}

- (void) delegatesPerformSelector:(SEL) selector withTimeIntervalAsFristParameter:(NSTimeinterval) timeInterval {
    for (id<ADelegateProtocol> delegate in delegates) {
        if([delegate respondsToSelector:selector]) {
            objc_msgSend(delegate, selector, timeInterval);
        }
    }
}

选择器作为参数传入，timeInterval 是一个非对象值.

The selector is passed in as a parameter, timeInterval is a non-object value.

注意:我不想使用 KVO.

Note: I don't want to use KVO.

推荐答案

如果你打算使用 objc_msgSend() 你必须创建一个正确类型转换的函数指针来这样做.依靠可变参数映射到非可变参数并非在所有情况下都有效.

If you are going to use objc_msgSend() you must create a correctly typecast function pointer to do so. Relying on varargs to map to non-varargs doesn't work in all cases.

即你会想要:

void (*myMessage)(id, SEL, NSTimeInterval) = objc_msgSend;
myMessage(delegate, aSelector, aTimeInterval);

(输入 SO - 将语法视为近似值.:)

(typed into SO -- consider the syntax an approximation. :)

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