洗牌在Objective-C數組

Question

可能重複：
What’s the Best Way to Shuffle an NSMutableArray?

我開發iPhone/iPad.I的應用程序要重新洗牌存儲在NSArray.Is有任何對象用objective-c實現它的方法？

Answer 1

類別添加到NSMutableArray裏，與code provided by Kristopher Johnson -

// NSMutableArray_Shuffling.h 

#if TARGET_OS_IPHONE 
#import <UIKit/UIKit.h> 
#else 
#include <Cocoa/Cocoa.h> 
#endif 

// This category enhances NSMutableArray by providing 
// methods to randomly shuffle the elements. 
@interface NSMutableArray (Shuffling) 
- (void)shuffle; 
@end 


// NSMutableArray_Shuffling.m 

#import "NSMutableArray_Shuffling.h" 

@implementation NSMutableArray (Shuffling) 

- (void)shuffle 
{ 

    static BOOL seeded = NO; 
    if(!seeded) 
    { 
    seeded = YES; 
    srandom(time(NULL)); 
    } 

    NSUInteger count = [self count]; 
    for (NSUInteger i = 0; i < count; ++i) { 
     // Select a random element between i and end of array to swap with. 
     int nElements = count - i; 
     int n = (random() % nElements) + i; 
     [self exchangeObjectAtIndex:i withObjectAtIndex:n]; 
    } 
} 

@end 

Answer 2

看看這個sample有幫助。

你可以看到這個以前的SO問題太canonical way to randomize an NSArray in Objective C