什么是最好的方式来洗牌一个NSMutableArray？

Question

什么是最好的方式来洗牌一个NSMutableArray？

如果你有NSMutableArray如何随机调整元素？

(我有我自己的答案，这是在下面，但我是新的可可，我有兴趣知道是否有更好的方法。)

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更新：截至iOS 10+和MacOS 10.12+，有一个-[NSMutableArray shuffledArray]方法，可用于洗牌。看见https：/developer.apple.com/Document/Foundation/nsArray/1640855-Shuffledarray？language=objc关于细节。(但请注意，这将创建一个新的数组，而不是对现有的元素进行洗牌。)

Answer 1

我通过向NSMutableArray添加一个类别来解决这个问题。编辑：删除不必要的方法，感谢Ladd的回答。编辑：变化(arc4random() % nElements)到arc4random_uniform(nElements)感谢Gregory Goltsov的答复，Miho和Blahdiblah的评论编辑：循环改进，感谢罗恩的评论编辑：添加检查该数组不为空，这要感谢Mahesh Agrawal的评论。//&nbsp;&nbsp;NSMutableArray_Shuffling.h#if&nbsp;TARGET_OS_IPHONE#import&nbsp;<UIKit/UIKit.h>#else#include&nbsp;<Cocoa/Cocoa.h>#endif //&nbsp;This&nbsp;category&nbsp;enhances&nbsp;NSMutableArray&nbsp;by&nbsp;providing //&nbsp;methods&nbsp;to&nbsp;randomly&nbsp;shuffle&nbsp;the&nbsp;elements.@interface&nbsp;NSMutableArray&nbsp;(Shuffling)-&nbsp;(void)shuffle;@end //&nbsp;&nbsp;NSMutableArray_Shuffling.m#import&nbsp;"NSMutableArray_Shuffling.h"@implementation&nbsp;NSMutableArray&nbsp;(Shuffling)-&nbsp;(void)shuffle{ &nbsp;&nbsp;&nbsp;&nbsp;NSUInteger&nbsp;count&nbsp;=&nbsp;[self&nbsp;count]; &nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(count&nbsp;<=&nbsp;1)&nbsp;return; &nbsp;&nbsp;&nbsp;&nbsp;for&nbsp;(NSUInteger&nbsp;i&nbsp;=&nbsp;0;&nbsp;i&nbsp;<&nbsp;count&nbsp;-&nbsp;1;&nbsp;++i)&nbsp;{ &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;NSInteger&nbsp;remainingCount&nbsp;=&nbsp;count&nbsp;-&nbsp;i; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;NSInteger&nbsp;exchangeIndex&nbsp;=&nbsp;i&nbsp;+&nbsp;arc4random_uniform((u_int32_t&nbsp;)remainingCount); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[self&nbsp;exchangeObjectAtIndex:i&nbsp;withObjectAtIndex:exchangeIndex]; &nbsp;&nbsp;&nbsp;&nbsp;}}@end