IOS开发之常用的正则表达式

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   iOS 中可以通过 NSPredicate 来处理正则表达式。相关资料如下：  NSPredicate 苹果官方文档： http://developer.apple.com/documentation/Cocoa/Conceptual/Predicates/predicates.html  Predicate format strings： http://developer.apple.com/documentation/Cocoa/Conceptual/Predicates/Articles/pSyntax.html  ICU 正则表达式规则： http://www.icu-project.org/userguide/regexp.html      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 ＝ @“[email protected]”；

    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。