从Array获取随机对象

Question

我想从数组中获取随机对象,有什么方法可以从可变数组中找到随机对象？

Answer 1

@interface NSArray (Random)
- (id) randomObject;
@end

@implementation NSArray (Random)

- (id) randomObject
{
     if ([self count] == 0) {
         return nil;
     }
     return [self objectAtIndex: arc4random() % [self count]];
}

@end

Answer 2

id obj;    
int r = arc4random() % [yourArray count];
    if(r<[yourArray count])
      obj=[yourArray objectAtIndex:r];
   else
   {
     //error message
   }

Answer 3

id randomObject = nil;
if ([array count] > 0){
    int randomIndex = arc4random()%[array count];
    randomObject = [array objectAtIndex:randomIndex];
}