IOS中NSPredicate和NSRegularExpression校验正则表达式区别

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 <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];
}

@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 <foundation/foundation.h>

@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

最后我们看到，还是推荐大家使用nsregularexpression来做正则的校验，如果大家在学习中有更好的解决方法或者心得，可以在下方的留言区讨论。