1.數(shù)組中隨機(jī)取出三個(gè)元素（有可能重復(fù)）
NSArray *array = [[NSArray alloc] initWithObjects:@"A",@"B",@"C",@"D",@"E",nil];
NSMutableArray *randomArray = [[NSMutableArray alloc] init];
while ([randomArray count] < 3) {
int r = arc4random() % [array count];
[randomArray addObject:[array objectAtIndex:r]];
}
2.數(shù)組中隨機(jī)取出不重復(fù)的三個(gè)元素，NSMutableSet中無論怎么添加重復(fù)的元素都會(huì)過濾掉只留一個(gè)元素
NSArray *array = [[NSArray alloc] initWithObjects:@"A",@"B",@"C",@"D",@"E",nil];
NSMutableSet *randomSet = [[NSMutableSet alloc] init];
while ([randomSet count] < 3) {
int r = arc4random() % [array count];
[randomSet addObject:[array objectAtIndex:r]];
}
NSArray *randomArray = [randomSet allObjects];
NSLog(@"%@",randomArray);
