如何在Swift中使用indicesOfObjectsPassingTest:

Question

indexOfObjectsPassingTest的声明:在Swift中看起来像这样

func indexesOfObjectsPassingTest(predicate: ((AnyObject!, Int, CMutablePointer<ObjCBool>) -> Bool)!) -> NSIndexSet!

我已经尝试了各种各样的排列来让它发挥作用,但我很难过,特别是你如何处理这件作品,CMutablePointer<ObjCBool>) -> Bool)!.我发现它很混乱,当我第一次在objective-c中学习块时,你如何从声明转换为实际使用方法,而Swift的语法至少是令人困惑的.

Answer 1

这段代码在我的游乐场工作;)希望它有点帮助

额外功能定义

import Cocoa

let list = [2, 3, 4, 5, 6, 7, 8]

func test (object: AnyObject!, index: Int, stop: CMutablePointer<ObjCBool>) -> Bool
{
    let number = object as Int
    return (number % 2 == 0) //for even numbers
}

let result: NSIndexSet = (list as NSArray).indexesOfObjectsPassingTest(test)

println("\(result.lastIndex)") //prints "6" (because 8%2=0)

直列关闭

我将上面的示例转换为内联闭包(在Swift-eBook中描述).参数列表和返回类型由术语分隔in.

import Cocoa

let list = [2, 3, 4, 5, 6, 7, 8]

let result: NSIndexSet = (list as NSArray).indexesOfObjectsPassingTest({
(object: AnyObject!, index: Int, stop: CMutablePointer<ObjCBool>) -> Bool in
    let number = object as Int
    return (number % 2 == 0) //for even numbers
})

println("\(result.lastIndex)") //prints "6" (because 8%2=0)