如何停止enumerateObjectsUsingBlock Swift

Question

如何停止块枚举？

    myArray.enumerateObjectsUsingBlock( { object, index, stop in
        //how do I stop the enumeration in here??
    })

我知道你在obj-c中这样做:

    [myArray enumerateObjectsUsingBlock:^(id *myObject, NSUInteger idx, BOOL *stop) {
        *stop = YES;
    }];

Answer 1

不幸的是,这改变了Swift的每个主要版本.这是一个细分:

斯威夫特1

stop.withUnsafePointer { p in p.memory = true }

斯威夫特2

stop.memory = true

斯威夫特3

stop.pointee = true

Answer 2

在Swift 1中:

stop.withUnsafePointer { p in p.memory = true }

在Swift 2中:

stop.memory = true

在Swift 3-4中:

stop.pointee = true

Answer 3

从XCode6 Beta4开始,可以使用以下方法:

let array: NSArray = // the array with some elements...

array.enumerateObjectsUsingBlock( { (object: AnyObject!, idx: Int, stop: UnsafePointer<ObjCBool>) -> Void in

        // do something with the current element...

        var shouldStop: ObjCBool = // true or false ...
        stop.initialize(shouldStop)

        })

Answer 4

接受的答案是正确的,但仅适用于NSArrays.不适用于Swift数据类型Array.如果您愿意,可以使用扩展程序重新创建它.

extension Array{
    func enumerateObjectsUsingBlock(enumerator:(obj:Any, idx:Int, inout stop:Bool)->Void){
        for (i,v) in enumerate(self){
            var stop:Bool = false
            enumerator(obj: v, idx: i,  stop: &stop)
            if stop{
                break
            }
        }
    }
}

称之为

[1,2,3,4,5].enumerateObjectsUsingBlock({
    obj, idx, stop in

    let x = (obj as Int) * (obj as Int)
    println("\(x)")

    if obj as Int == 3{
        stop = true
    }
})

或者用于作为最后一个参数的块的功能

[1,2,3,4,5].enumerateObjectsUsingBlock(){
    obj, idx, stop in

    let x = (obj as Int) * (obj as Int)
    println("\(x)")

    if obj as Int == 3{
        stop = true
    }
}