在@selector()中传递一个块 [英] passing a block in @selector()

问题描述

如何在方法incrementCount:completion中传递块，以及它的外观如何，以使属性self.count在CounterClass中递增后返回?我不确定在方法中定义块参数(void(^)(void))callback;的方式是否正确，即是否也应该有返回值?

How do I pass a block, and what would it look like, in the method incrementCount:completion to get the property self.count returned after its increment in the CounterClass? I'm not sure if the way I defined the block parameter (void(^)(void))callback; in the method is correct i.e. should it also have a return value?

ViewController

ViewController

 [NSTimer scheduledTimerWithTimeInterval:3.0
                                         target:self.counterClass
                                       selector:@selector(incrementCount:completion:)
                                       userInfo:nil
                                        repeats:YES];

CounterClass

CounterClass

-(void)incrementCount:(NSTimer *)timer completion:(void(^)(void))callback;
    {
        self.count += 1;

    }

推荐答案

NSTimer期望调用一个带有零个或一个参数的方法，如果有参数，则它应该是计时器实例本身.

NSTimer expects to call a method which takes zero or one parameters, if there is a parameter it should be the timer instance itself.

因此，您无法使用带有2个参数的方法，其中一个是一个块.

So, you can't have a method with 2 parameters where one is a block.

相反，删除第二个参数，然后仅调用方法实现中的另一个方法或块.该块可以存储为该类的@property.

Instead, remove the second parameter and simply call another method or block in the method implementation. The block could be stored as an @property of the class.

这篇关于在@selector()中传递一个块的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！