IOS開發之常用的正則表達式

在 iOS 中，我們使用 NSPredicate 的字符串比較功能來進行正則表達式處理，其比較關鍵字為：MATCHES

下面，列舉一個匹配6-15個由字母/數字組成的字符串的正則表達式，來看看 NSPredicate 的具體使用：

    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則表達式
//郵箱  
+ (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];  
}  


//手機號碼驗證  
+ (BOOL) validateMobile:(NSString *)mobile  
{  
    //手機號以13， 15，18開頭，八個 \d 數字字符  
    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];  
}  


//車牌號驗證  
+ (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];  
}  


//車型  
+ (BOOL) validateCarType:(NSString *)CarType  
{  
    NSString *CarTypeRegex = @"^[\u4E00-\u9FFF]+$";  
    NSPredicate *carTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",CarTypeRegex];  
    return [carTest evaluateWithObject:CarType];  
}  


//用戶名  
+ (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;  
}  


//密碼  
+ (BOOL) validatePassword:(NSString *)passWord  
{  
    NSString *passWordRegex = @"^[a-zA-Z0-9]{6,20}+$";  
    NSPredicate *passWordPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",passWordRegex];  
    return [passWordPredicate evaluateWithObject:passWord];  
}  


//昵稱  
+ (BOOL) validateNickname:(NSString *)nickname  
{  
    NSString *nicknameRegex = @"^[\u4e00-\u9fa5]{4,8}$";  
    NSPredicate *passWordPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",nicknameRegex];  
    return [passWordPredicate evaluateWithObject:nickname];  
}  


//身份證號  
+ (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];  
}  

其實iOS中有三種方式來實現正則表達式的匹配。現在將他們都記錄在這里：

1.利用NSPredicate（謂詞）匹配

例如匹配有效郵箱：

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];

謂詞匹配比較靈活，但是需要有謂詞的相關知識。

2.利用rangeOfString：option：直接查找

    NSString *searchText = @"http:// 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中設定NSRegularExpressionSearch就是表示利用正則表達式匹配，會返回第一個匹配結果的位置。

3.使用正則表達式類

    NSString *searchText = @"http:// 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]);

    }

使用系統的正則表達式類（NSRegularExpression）會返回匹配的多個結果。

小結：

第一種匹配需要學習NSPredicate的寫法，需要查閱蘋果相關技術文檔；如果只關心第一個匹配的結果，第二種匹配較為簡潔；如果需要匹配多個結果，同時匹配多次，第三種方式效率會更高。