一，代码：
- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. NSLog(@"---产生随机字符串---%@",[self generateTradeNO]); } //产生随机字符串 - (NSString *)generateTradeNO { static int kNumber = 15; NSString *sourceStr = @"0123456789ABCDEFGHIJKLMNOPQRST"; NSMutableString *resultStr = [[NSMutableString alloc] init]; srand(time(0)); for (int i = 0; i < kNumber; i++) { unsigned index = rand() % [sourceStr length]; NSString *oneStr = [sourceStr substringWithRange:NSMakeRange(index, 1)]; [resultStr appendString:oneStr]; } return resultStr; }
二，输出：
2015-10-23 10:04:22.908 产生随机字符串[974:46634] ---产生随机字符串---DQA5AGLNIBD52KQ