obective-c产生不同的随机数 方法

-(void)randifferentNumber:(int)n from:(int)allNumber

{

diffArray = [[NSMutableArray alloc]initWithCapacity:n];

NSMutableArray *array =[NSMutableArray arrayWithCapacity:allNumber];

for(int index=0;index<allNumber;index++)

{

[array addObject:[NSNumber numberWithInt:index+1]];

}

for (int index=0; index<n; index++) {

int rand = arc4random()%allNumber;

allNumber--;

int place = [(NSNumber*)[array objectAtIndex:rand]intValue];

[array removeObjectAtIndex:rand];

[diffArray addObject:[NSNumber numberWithInt:place]];

}

[array removeAllObjects];

array = Nil;

}