Question

I have done I custom class method for NSString to md5 a NSString.
This is my code:

NSString+CustomMethod.h

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>


@interface NSString (CustomMethod)

+ (NSString*)MD5:(NSString *)string;
@end

NSString+CustomMethod.m

#import "NSString+CustomMethod.h"

@implementation NSString (CustomMethod)

+ (NSString*)MD5:(NSString *)string
{
    // Create pointer to the string as UTF8
    const char *ptr = [string UTF8String];

    // Create byte array of unsigned chars
    unsigned char md5Buffer[CC_MD5_DIGEST_LENGTH];

    // Create 16 byte MD5 hash value, store in buffer
    CC_MD5(ptr, strlen(ptr), md5Buffer);

    // Convert MD5 value in the buffer to NSString of hex values
    NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++) 
        [output appendFormat:@"%02x",md5Buffer[i]];

    return output;
}


@end

This Methodclass works great, but compiler give me a warring:

warning: class method ‘+MD5:’ not found (return type defaults to ‘id’) [3]

How can I remove this warning ??

PS: if a put #import “NSString+CustomMethod.h” no warning is shown, but it’s a workAround, I have created a custom method class not to include my custom class everywhere I need it

Thanks for any helps !!

Answer 1

Put #import "NSString+CustomMethod.h" in .pch file or in file where you want to use it.