Objective-c '-makeObjectsPerformSelector:'

Posted on | In |

-makeObjectsPerformSelector: 方法

当我们需要对NSArray or NSSet里面的对象，执行同一个操作的时候，我们首先想到的可能是 for 循环。其实对于NSArray 和 NSSet 都有个一简便的方法:

-makeObjectsPerformSelector:，数组里面的元素同时执行某个 selector。-makeObjectsPerformSelector:withObject:可以带一个参数。例如移除某个视图的所有subview，只要一句话：

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[self.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];

既然提到了循环，我们就总结一下，数组中其他几种常用的循环方式：

for in

for (id obj in array){
}

Block Enumeration

[array enumerateObjectsUsingBlock: ^(id obj, NSUInteger     idx, BOOL *stop) {
}];
//Concurrent:
[array enumerateObjectsWithOptions:     NSEnumerationConcurrent usingBlock: ^(id obj, NSUInteger idx, BOOL *stop) { 
}];

GCD

GCD apply:

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dispatch_queue_t queue = dispatch_get_global_queue(0, 0);

//sync:
dispatch_apply([array count], queue, ^(size_t idx) {
    id obj = [array objectAtIndex: idx];
    
});

//Async:
dispatch_async(queue, ^(void) {
    dispatch_apply([array count], queue, ^(size_t idx) {
        id obj = [array objectAtIndex: idx];
    });
});