使用示例

1 首先需要创建一个NSRegularExpression的对象

NSError *error = NULL;
NSString *str = @"AABCfaabcf";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"abc" options:NSRegularExpressionCaseInsensitive error:&error];
NSRange range = NSMakeRange(0, str.length);
if (error) {
    NSLog(@"error : %@", error);
    return;
}

2 查看匹配情况

    //******    匹配数量        *******
    NSUInteger numberOfMatches = [regex numberOfMatchesInString:str options:0 range:range];
    //匹配的数量 输出 2
    NSLog(@"numberOfMatches is %lu", (unsigned long)numberOfMatches);
    
    //******    第一个匹配        *******
    NSRange firstRange = [regex rangeOfFirstMatchInString:str options:0 range:range];
    if (firstRange.location != NSNotFound) {
        NSString *firstRangeStr = [str substringWithRange:firstRange];
        //打印 ABC
        NSLog(@"firstRangeStr is %@", firstRangeStr);
    }

    //******    第一个匹配        *******
    NSTextCheckingResult *result = [regex firstMatchInString:str options:0 range:range];
    if (result) {
        NSString *firstRangeStr = [str substringWithRange:firstRange];
        //打印 ABC
        NSLog(@"firstMatchInString is %@", firstRangeStr);
    }
    
    //如果没有任何匹配的数据，则range.location = NSNotFound
    //可以根据这个值来判断是否有匹配的数据
    NSString *notfoundStr = @"test";
    NSRange notfoundRange = [regex rangeOfFirstMatchInString:notfoundStr options:0 range:NSMakeRange(0, notfoundStr.length)];
    if (notfoundRange.location == NSNotFound) {
        NSLog(@"没有对应的数据");
    }
    
    //******    所有匹配        *******
    NSArray *matches = [regex matchesInString:str options:0 range:range];
    for (NSTextCheckingResult *match in matches) {
        NSRange matchRange = match.range;
        NSString *rangeStr = [str substringWithRange:matchRange];
        NSLog(@"rangeStr is %@", rangeStr);
    }
    
    //******    枚举匹配        *******
    __block NSUInteger count = 0;
    [regex enumerateMatchesInString:str options:0 range:range usingBlock:^(NSTextCheckingResult * _Nullable result, NSMatchingFlags flags, BOOL * _Nonnull stop) {
        NSRange matchRange = result.range;
        NSLog(@"enumerate match %@", [str substringWithRange:matchRange]);
        
        //下面这句话表示匹配数量有一个的时候，就跳出这个枚举
        if (++count >= 1) {
            *stop = YES;
        }
    }];

3 查找并替换

//如果需要部分替换，则需要修改range的范围
    NSString *modifiedString = [regex stringByReplacingMatchesInString:str options:0 range:range withTemplate:@"JC"];
    //原来AABCfaabcf
    //完成AJCfaJCf
    NSLog(@"modifiedString is %@", modifiedString);
    
    //原来AABCfaabcf
    //完成CJH
    NSString *replaceCheckingResultString = [regex replacementStringForResult:matches.firstObject inString:str offset:0 template:@"CJH"];
    NSLog(@"replaceCheckingResultString is %@", replaceCheckingResultString);
    
    //替换的次数
    NSUInteger replaceCount = [regex replaceMatchesInString:[str mutableCopy] options:0 range:range withTemplate:@"JC"];
    NSLog(@"replaceCount is %lu", (unsigned long)replaceCount);

技巧

1 去除输入字符串中前面和后面的空格，有时候用户可能在开始输入的时候打了一个空格但用户自己并没有发现

// Trim the input string by removing leading and trailing white spaces
// and return the result
- (NSString *)stringTrimmedForLeadingAndTrailingWhiteSpacesFromString:(NSString *)string
{
    NSString *leadingTrailingWhiteSpacesPattern = @"(?:^\\s+)|(?:\\s+$)";
    
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:leadingTrailingWhiteSpacesPattern options:NSRegularExpressionCaseInsensitive error:NULL];
    
    NSRange stringRange = NSMakeRange(0, string.length);
    NSString *trimmedString = [regex stringByReplacingMatchesInString:string options:NSMatchingReportProgress range:stringRange withTemplate:@"$1"];
    
    return trimmedString;
}