在代码开发过程中，我们经常需要用来校验邮箱、手机号等等，这个时候就需要用到正则表达式。在iOS开发中，能用来做正则校验的有两个 NSPredicate 和 NSRegularExpression 。

NSPredicate

NSPredicate 能用来简单做正则校验，但是它的问题是存在校验不出来的情况。

//NSString+RegEx.h#import 
    
     @interface NSString (RegEx)#pragma mark - NSPredicate- (BOOL)mars_matchedByPrdicateToRegEx:(NSString *)regEx;@end//NSString+RegEx.m#import "NSString+RegEx.h"@implementation NSString (RegEx)#pragma mark - NSPredicate- (BOOL)mars_matchedByPrdicateToRegEx:(NSString *)regEx{    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regEx];    return [predicate evaluateWithObject:self];}@end
    

NSRegularExpression （推荐）

NSRegularExpression 相对于 NSPredicate 功能就强大的多了，这也是iOS正则校验的正统路子。

//NSString+RegEx.h#import 
    
     @interface NSString (RegEx)#pragma mark - NSRegularExpression//校验是否匹配- (BOOL)mars_matchedToRegEx:(NSString *)regEx;//匹配到的第一个字符串- (NSString *)mars_firstMatchToRegEx:(NSString *)regEx;//所有匹配的字符串- (NSArray *)mars_matchesToRegEx:(NSString *)regEx;//替换匹配到的字符串- (NSString *)mars_stringByReplaceMatchesToRegEx:(NSString *)regEx replaceString:(NSString *)replaceString;@end//NSString+RegEx.m#import "NSString+RegEx.h"@implementation NSString (RegEx)#pragma mark - NSRegualrExpression//校验是否匹配- (BOOL)mars_matchedToRegEx:(NSString *)regEx{        NSError *error;    NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];        NSUInteger number = [regularExpression numberOfMatchesInString:self options:0 range:NSMakeRange(0, self.length)];    return number != 0;}//匹配到的第一个字符串- (NSString *)mars_firstMatchToRegEx:(NSString *)regEx{    NSError *error;    NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];    NSTextCheckingResult *firstMatch = [regularExpression firstMatchInString:self options:0 range:NSMakeRange(0, self.length)];    if (firstMatch) {        NSString *result = [self substringWithRange:firstMatch.range];        return result;    }    return nil;}//所有匹配的字符串- (NSArray *)mars_matchesToRegEx:(NSString *)regEx{    NSError *error;    NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];        NSArray *matchArray = [regularExpression matchesInString:self options:0 range:NSMakeRange(0, self.length)];        NSMutableArray *array = [NSMutableArray array];    if (matchArray.count != 0) {        for (NSTextCheckingResult *match in matchArray) {            NSString *result = [self substringWithRange:match.range];            [array addObject:result];        }    }        return array;}//替换匹配到的字符串- (NSString *)mars_stringByReplaceMatchesToRegEx:(NSString *)regEx replaceString:(NSString *)replaceString{    NSError *error;    NSRegularExpression *regularExpression = [NSRegularExpression regularExpressionWithPattern:regEx options:NSRegularExpressionCaseInsensitive error:&error];    return [regularExpression stringByReplacingMatchesInString:self options:0 range:NSMakeRange(0, self.length) withTemplate:replaceString];}@end