字符输入限制---正则

(?![0-9]+$)代表如果是0-9的字符就不匹配;
[0-9a-zA-Z]代表如果是0-9,a-z,A-Z的字符三种同时存在就匹配;
代表位数不限制,如果需要限制位数,将替换成{2,10};

+ (void)passwordLimit:(NSString* )password{//密码要求大小写数字，位数看清况
//    NSPredicate *digitalReg = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",  @"^[0-9a-zA-Z]*$"];
//    NSPredicate *digitalReg = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",  @"^[0-9a-zA-Z]{2,5}$"];
    NSPredicate *digitalReg = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",  @"^(?![0-9]+$)(?![a-zA-Z]+$)(?![a-z0-9]+$)(?![0-9A-Z]+$)[0-9A-Za-z]*$"];
    
    BOOL digitalFlag = [digitalReg evaluateWithObject:password];
    if (digitalFlag) {
        DLog(@"成功");
    }else{
        DLog(@"失败");
    }
}