如何将@selector作为参数传递？ [英] How to I pass @selector as a parameter?

问题描述

对于方法：

[NSThread detachNewThreadSelector:@selector(method:) toTarget:self withObject:(id)SELECTOR];

如何传入@selector？我尝试将它转换为（id）以使其编译，但它在运行时崩溃。

How do I pass in a @selector? I tried casting it to (id) to make it compile, but it crashes in runtime.

更具体地说，我有这样的方法：

More specifically, I have a method like this:

+(void)method1:(SEL)selector{
[NSThread detachNewThreadSelector:@selector(method2:) toTarget:self withObject:selector];   
}

它崩溃了。如何在没有崩溃的情况下传入选择器，以便新线程可以在线程就绪时调用选择器？

It crashes. How do I pass in the selector without crashing, so that the new thread can call the selector when the thread is ready?

推荐答案

这里的问题不是将选择器传递给方法本身，而是将选择器传递给期望对象。要将非对象值作为对象传递，可以使用 NSValue 。在这种情况下，您需要创建一个接受NSValue并检索适当选择器的方法。这是一个示例实现：

The problem here isn't passing a selector to a method, per se, but passing a selector where an object is expected. To pass a non-object value as an object, you can use NSValue. In this case, you'll need to create a method that accepts an NSValue and retrieves the appropriate selector. Here's an example implementation:

@implementation Thing
- (void)method:(SEL)selector {
    // Do something
}

- (void)methodWithSelectorValue:(NSValue *)value {
    SEL selector;

    // Guard against buffer overflow
    if (strcmp([value objCType], @encode(SEL)) == 0) {
        [value getValue:&selector];
        [self method:selector];
    }
}

- (void)otherMethodShownInYourExample {
    SEL selector = @selector(something);
    NSValue *selectorAsValue = [NSValue valueWithBytes:&selector objCType:@encode(SEL)];
    [NSThread detachNewThreadSelector:@selector(methodWithSelectorValue:) toTarget:self withObject:selectorAsValue];
}
@end

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