如何在Swift中使用indexesOfObjectsPassingTest：

本文介绍了如何在Swift中使用indexesOfObjectsPassingTest：的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

indexesOfObjectsPassingTest的声明：在Swift中如下所示：

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

我试过各种排列方式让这个工作，但我很沮丧，特别是你如何处理这一块， CMutablePointer< ObjCBool​​>） - > Bool）！。我发现它很混乱，当我第一次学习块objective-c，如何从声明转换为实际使用的方法，并且Swift的语法至少是混乱。

<这个代码在我的工作在Playground;）希望它帮助一点

额外的功能 - 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））//输出6（因为8％2 = 0）

Inline-Closure

与内联闭包（在Swift电子书中描述）。参数列表和返回类型由中的项分隔。

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 let number = object as Int return（number％2 == 0）// for even numbers }） println（\ lastIndex））//打印6（因为8％2 = 0）

The declaration of indexesOfObjectsPassingTest: looks like this in Swift,

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

I've tried all sorts of permutations to get this to work, but I'm stumped, particularly with how you deal with this piece, CMutablePointer<ObjCBool>) -> Bool)!. I found it confusing enough, when I was first learning blocks in objective-c, how you translate from the declaration to actual use of a method, and the syntax of Swift is at least as confusing.

解决方案

This code is working in the Playground for me ;) Hope it helps a bit

Extra Function-Definition

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)

Inline-Closure

I transformed my above example to work with an inline-closure (described in the Swift-eBook). The parameter-list and return-type is separated by the term 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)