在代碼開發過程中，我們經常需要用來校驗郵箱、手機號等等，這個時候就需要用到正則表達式。在iOS開發中，能用來做正則校驗的有兩個 NSPredicate 和 NSRegularExpression 。
NSPredicate 能用來簡單做正則校驗，但是它的問題是存在校驗不出來的情況。
//NSString+RegEx.h#import <Foundation/Foundation.h>@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];}@endNSRegularExpression 相對于 NSPredicate 功能就強大的多了，這也是iOS正則校驗的正統路子。
//NSString+RegEx.h#import <Foundation/Foundation.h>@interface NSString (RegEx)#pragma mark - NSRegularExpression//校驗是否匹配- (BOOL)mars_matchedToRegEx:(NSString *)regEx;//匹配到的第一個字符串- (NSString *)mars_firstMatchToRegEx:(NSString *)regEx;//所有匹配的字符串- (NSArray *)mars_matchesToRegEx:(NSString *)regEx;//替換匹配到的字符串- (NSString *)mars_stringByReplaceMatchesToRegEx:(NSString *)regEx replaceString:(NSString *)replaceString;@end//NSString+RegEx.m#import "NSString+RegEx.h"@implementation NSString (RegEx)#pragma mark - NSRegualrExpression//校驗是否匹配- (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;}//匹配到的第一個字符串- (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;}//替換匹配到的字符串- (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最后我們看到，還是推薦大家使用NSRegularExpression來做正則的校驗，如果大家在學習中有更好的解決方法或者心得，可以在下方的留言區討論。
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