在快速的代理数组中查找委托

Question

我想在删除之前检查我的removeDelegate方法中是否已有委托.我怎么做？

这是我到目前为止所得到的:

protocol LocationManagerDelegate {
    func locationManagerDidUpdateLocation(
        oldLocation: CLLocationCoordinate2D,
        currentLocation: CLLocationCoordinate2D
    )
}

class LocationManager: NSObject {
    private var _delegates = [LocationManagerDelegate]()

    func removeDelegate(delegate:LocationManagerDelegate) {
        if contains(_delegates, delegate) {
            // Remove delegate
        }
    }
}

但是,这会在'if contains'行中给出以下错误:

不能使用类型'(@lvalue Array <LocationManagerDelegate>!,LocationManagerDelegate)'的参数列表调用'contains'

Answer 1

Swift 3更新:

假设委托实际上是一个类的实例,你可以在协议中要求"继承""class":

protocol LocationManagerDelegate: class {
    // ...
}

然后使用该index(where:)方法,使用"indentitiy运算符 ===:

class LocationManager: NSObject {
    private var _delegates = [LocationManagerDelegate]()

    func removeDelegate(delegate:LocationManagerDelegate) {
        if let index = _delegates.index(where: { $0 === delegate }) {
            _delegates.remove(at: index)
        }
    }
}

老答案(斯威夫特1):

contains()功能略有不同:

func contains<S : SequenceType where S.Generator.Element : Equatable>(seq: S, x: S.Generator.Element) -> Bool

func contains<S : SequenceType, L : BooleanType>(seq: S, predicate: (S.Generator.Element) -> L) -> Bool

您正在使用第一个,它要求序列元素符合Equatable协议,即可以与它们进行比较==.

假设委托实际上是一个类的实例,你可以在协议中要求"继承""class":

protocol LocationManagerDelegate : class {
    // ...
}

然后使用contains()身份运算符的第二个基于谓词的版本===:

func removeDelegate(delegate:LocationManagerDelegate) {
    if contains(_delegates, { $0 === delegate }) {
        // Remove delegate
    }
}

要从数组中删除对象,您必须获取其索引,因此您可以使用/sf/answers/1788015911/中的findIdenticalObject()函数:

func findIdenticalObject<T : AnyObject>(array: [T], value: T) -> Int? {
    for (index, elem) in enumerate(array) {
        if elem === value {
            return index
        }
    }
    return nil
}

然后从数组中查找和删除

func removeDelegate(delegate:LocationManagerDelegate) {
    if let index = findIdenticalObject(_delegates, delegate) {
        _delegates.removeAtIndex(index)
    }
}