ios - 在 IOS 上创建随机字母数字

Question

我是 Java 程序员，“必须”转向 obj-C 一段时间，

我在生成随机字母数字代码时有些困惑...这是我的 javacode:

PS:我想生成这样的代码:Gh12PU67、AC88pP13、Bk81gH89

private String generateCode(){
 String code = "";
 Random r = new Random();
 char[] c = new char[]{'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

 for(int i = 0; i<4; i++){
  int uplow = r.nextInt(2);
  String temp = ""+ c[r.nextInt(c.length)];
  if(uplow==1)
   code = code + temp.toUpperCase();
 else
   code = code + temp;

 if((i+1)%2==0){
   code += r.nextInt(10);
   code += r.nextInt(10);
 }
}

return code;
}

然后我在 OBJ-C 上创建

-(void)generateCode{
    NSString *alphabet  = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXZY0123456789";
    NSMutableString *s = [NSMutableString stringWithCapacity:4];
    for (NSUInteger i = 0U; i < 4; i++) {
        u_int32_t r = arc4random() % [alphabet length];
        unichar c = [alphabet characterAtIndex:r];
        [s appendFormat:@"%C", c];

    }
    NSLog(@"s-->%@",s);
}

但我得到的结果是“HpNz” AC88pP13 insted hve pattern String,string, numeric,numeric, lowescase string,numeric,numeric...

那个案子毁了我 3 天的生活......

Answer 1

您的 Objective-C 代码看起来不错，但是(正如@Wain 在上面的评论中正确所说)，Java 函数函数包含在 2 个字母后插入 2 个数字的逻辑，您可以尚未在 Objective-C 方法中复制。

我会让这个逻辑稍微不那么晦涩，然后把它写成

- (void)generateCode
{
    static NSString *letters = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXZY";
    static NSString *digits = @"0123456789";
    NSMutableString *s = [NSMutableString stringWithCapacity:8];
    for (NSUInteger i = 0; i < 2; i++) {
        uint32_t r;

        // Append 2 random letters:
        r = arc4random_uniform((uint32_t)[letters length]);
        [s appendFormat:@"%C", [letters characterAtIndex:r]];
        r = arc4random_uniform((uint32_t)[letters length]);
        [s appendFormat:@"%C", [letters characterAtIndex:r]];

        // Append 2 random digits:
        r = arc4random_uniform((uint32_t)[digits length]);
        [s appendFormat:@"%C", [digits characterAtIndex:r]];
        r = arc4random_uniform((uint32_t)[digits length]);
        [s appendFormat:@"%C", [digits characterAtIndex:r]];

    }
    NSLog(@"s-->%@",s);
}

备注(来自手册页):arc4random_uniform(length) 优于 arc4random() % length，因为当上限不是 2 的幂时，它避免了“模数偏差”。

备注:Java 代码的更逐字翻译 code += r.nextInt(10);到 Objective-C 将是

r = arc4random_uniform(10);
[s appendString:[@(r) stringValue]];

它根据随机数创建一个 NSNumber 对象 @(r)，然后将其转换为字符串。