NSString regular expression replace

NSString+RegExp.h

@interface NSString (RegExp)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wstrict-prototypes"
- (NSString *)reg_replace:(NSRegularExpression *)regexp withBlock:(NSString *(NS_NOESCAPE ^)())block;
- (NSString *)reg_replacePattern:(NSString *)pattern withBlock:(NSString *(NS_NOESCAPE ^)())block;
#pragma clang diagnostic pop
@end

NSString+RegExp.m

#import "NSString+RegExp.h"

FOUNDATION_EXTERN bool _Block_has_signature(id);
FOUNDATION_EXTERN const char * _Block_signature(id);


@implementation NSString (RegExp)

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wstrict-prototypes"
- (NSString *)reg_replacePattern:(NSString *)pattern withBlock:(NSString *(NS_NOESCAPE ^)())block
{
    return [self reg_replace:[NSRegularExpression regularExpressionWithPattern:pattern
                                                                       options:0
                                                                         error:NULL]
                   withBlock:block];
}

- (NSString *)reg_replace:(NSRegularExpression *)regexp withBlock:(NSString *(NS_NOESCAPE ^)())block
#pragma clang diagnostic pop
{
    NSParameterAssert(regexp);
    NSParameterAssert(block);
    NSParameterAssert(_Block_has_signature(block));
    
    __block NSMutableString *newString = [NSMutableString stringWithCapacity:self.length];
    __block NSUInteger offset = 0;
    [regexp enumerateMatchesInString:self
                             options:0
                               range:NSMakeRange(0, self.length)
                          usingBlock:^(NSTextCheckingResult * _Nullable result, NSMatchingFlags flags, BOOL * _Nonnull stop) {
                              NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[NSMethodSignature signatureWithObjCTypes:_Block_signature(block)]];
                              NSUInteger numberOfArguments = invocation.methodSignature.numberOfArguments;
                              [invocation setTarget:[block copy]];
                              
                              __autoreleasing NSString *string = self;
                              [invocation setArgument:&string atIndex:1];
                              
                              NSRange range = result.range;
                              [invocation setArgument:&range atIndex:2];
                              
                              string = [self substringWithRange:range];
                              [invocation setArgument:&string atIndex:3];
                              
                              NSUInteger count = MIN([result numberOfRanges], numberOfArguments - 3);
                              for (NSUInteger i = 1; i < count; ++i) {
                                  NSRange range = [result rangeAtIndex:i];
                                  NSString *substr = [self substringWithRange:range];
                                  [invocation setArgument:&substr atIndex:i + 3];
                              }
                              [invocation invoke];
                              [invocation getReturnValue:&string];
                              
                              [newString appendString:[self substringWithRange:NSMakeRange(offset, range.location - offset)]];
                              [newString appendString:string];
                              offset = range.location + range.length;
                          }];
    [newString appendString:[self substringWithRange:NSMakeRange(offset, self.length - offset)]];
    return newString;
}

@end