OC

//隨機(jī)字母
- (NSString *)randomStringWithNumber:(NSInteger)number{ //number 是需要的個(gè)數(shù)
    NSString *ramdom;
    NSMutableArray *array = [NSMutableArray array];
    for (int i = 1; i ; i ++) {
    int a = (arc4random() % 122); //如需要可以改變數(shù)值大小  這兒的數(shù)值是ASCII值
    if (a > 96) { //這兒是小寫(xiě)字母 如需要自行更改
        char c = (char)a;
        [array addObject:[NSString stringWithFormat:@"%c",c]];
        if (array.count == number) {
            break;
        }
    } else continue;
    }
    ramdom = [array componentsJoinedByString:@""];//這個(gè)是把數(shù)組轉(zhuǎn)換為字符串 
    return ramdom;
}

swift

/** 隨機(jī)產(chǎn)生字符串
        parameters:
        - number 字符串長(zhǎng)度
        - digital 是否包含數(shù)字
        - capital 是否包含大寫(xiě)
        - lowercase 是否包含小寫(xiě)
     */
    class func getRandomString(_ number:Int! ,_ digital:Bool!,_ capital:Bool!,_ lowercase:Bool!) -> String{
        var number:Int! = number
        if number < 1 {
            number = 32
        }
        
        var strArray:Array<String> = Array()
        for _ in 0...INT64_MAX {
            let a:Int = Int(arc4random() % 122)
            let c:Character = Character(UnicodeScalar(a)!)
            //包含數(shù)字
            if digital {
                if a > 47 && a < 58{
                     strArray.append(String.init(c))
                }
            }
            //大寫(xiě)字母
            if capital {
                if a > 64 && a < 92 {
                    strArray.append(String.init(c))
                }
            }
            //小寫(xiě)字母
            if lowercase {
                if a > 96 && a < 123 {
                    strArray.append(String.init(c))
                }
            }
            if strArray.count == number{
                break
            }
        }
        let str:String = strArray.joined(separator: "")
        return str;
    }

自己照?qǐng)D更改數(shù)值（有些我不確定能行哦?。?/p>

ASCII表.png