IOS开发之常用的正则表达式

在 iOS 中，我们使用 NSPredicate 的字符串比较功能来进行正则表达式处理，其比较关键字为：MATCHES

下面，列举一个匹配6-15个由字母/数字组成的字符串的正则表达式，来看看 NSPredicate 的具体使用：

    NSString * regex        = @"(^[A-Za-z0-9]{6,15}$)";        NSPredicate * pred      = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];        BOOL isMatch            = [pred evaluateWithObject:@"123456ABCde"];  

下面是一些常用的正则表达式  //邮箱    + (BOOL) validateEmail:(NSString *)email    {        NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";        NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];        return [emailTest evaluateWithObject:email];    }            //手机号码验证    + (BOOL) validateMobile:(NSString *)mobile    {        //手机号以13， 15，18开头，八个 \d 数字字符        NSString *phoneRegex = @"^((13[0-9])|(15[^4,\\D])|(18[0,0-9]))\\d{8}$";        NSPredicate *phoneTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",phoneRegex];        return [phoneTest evaluateWithObject:mobile];    }            //车牌号验证    + (BOOL) validateCarNo:(NSString *)carNo    {        NSString *carRegex = @"^[\u4e00-\u9fa5]{1}[a-zA-Z]{1}[a-zA-Z_0-9]{4}[a-zA-Z_0-9_\u4e00-\u9fa5]$";        NSPredicate *carTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",carRegex];        NSLog(@"carTest is %@",carTest);        return [carTest evaluateWithObject:carNo];    }            //车型    + (BOOL) validateCarType:(NSString *)CarType    {        NSString *CarTypeRegex = @"^[\u4E00-\u9FFF]+$";        NSPredicate *carTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",CarTypeRegex];        return [carTest evaluateWithObject:CarType];    }            //用户名    + (BOOL) validateUserName:(NSString *)name    {        NSString *userNameRegex = @"^[A-Za-z0-9]{6,20}+$";        NSPredicate *userNamePredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",userNameRegex];        BOOL B = [userNamePredicate evaluateWithObject:name];        return B;    }            //密码    + (BOOL) validatePassword:(NSString *)passWord    {        NSString *passWordRegex = @"^[a-zA-Z0-9]{6,20}+$";        NSPredicate *passWordPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",passWordRegex];        return [passWordPredicate evaluateWithObject:passWord];    }            //昵称    + (BOOL) validateNickname:(NSString *)nickname    {        NSString *nicknameRegex = @"^[\u4e00-\u9fa5]{4,8}$";        NSPredicate *passWordPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",nicknameRegex];        return [passWordPredicate evaluateWithObject:nickname];    }            //身份证号    + (BOOL) validateIdentityCard: (NSString *)identityCard    {        BOOL flag;        if (identityCard.length <= 0) {            flag = NO;            return flag;        }        NSString *regex2 = @"^(\\d{14}|\\d{17})(\\d|[xX])$";        NSPredicate *identityCardPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex2];        return [identityCardPredicate evaluateWithObject:identityCard];    }  

其实iOS中有三种方式来实现正则表达式的匹配。现在将他们都记录在这里：

1.利用NSPredicate（谓词）匹配

例如匹配有效邮箱：

NSString ＊email ＝ @“nijino_saki@163.com”；

    NSString *regex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];

    BOOL isValid = [predicate evaluateWithObject:email];

谓词匹配比较灵活，但是需要有谓词的相关知识。

2.利用rangeOfString：option：直接查找

    NSString *searchText = @"// Do any additional setup after loading the view, typically from a nib.";

    NSRange range = [searchText rangeOfString:@"(?:[^,])*\\." options:NSRegularExpressionSearch];

    if (range.location != NSNotFound) {

        NSLog(@"%@", [searchText substringWithRange:range]);

    }

options中设定NSRegularExpressionSearch就是表示利用正则表达式匹配，会返回第一个匹配结果的位置。

3.使用正则表达式类

    NSString *searchText = @"// Do any additional setup after loading the view, typically from a nib.";    

    NSError *error = NULL;

    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?:[^,])*\\." options:NSRegularExpressionCaseInsensitive error:&error];

    NSTextCheckingResult *result = [regex firstMatchInString:searchText options:0 range:NSMakeRange(0, [searchText length])];

    if (result) {

        NSLog(@"%@\n", [searchText substringWithRange:result.range]);

    }

使用系统的正则表达式类（NSRegularExpression）会返回匹配的多个结果。

小结：

第一种匹配需要学习NSPredicate的写法，需要查阅苹果相关技术文档；如果只关心第一个匹配的结果，第二种匹配较为简洁；如果需要匹配多个结果，同时匹配多次，第三种方式效率会更高。