------------------.h文件--------------------

#import<Foundation/Foundation.h>

@interface NSString (SHA256)

- (NSString *)SHA256;

@end

-----------------------------------------------

#import "NSString+SHA256.h"

#import

@implementation NSString (SHA256)

-------------------------.m文件---------------------------------

#import "NSString+SHA256.h"

#import<CommonCrypto/CommonDigest.h>

- (NSString *)SHA256

{

const char *s = [self cStringUsingEncoding:NSASCIIStringEncoding];

NSData *keyData = [NSData dataWithBytes:s length:strlen(s)];

uint8_t digest[CC_SHA256_DIGEST_LENGTH] = {0};

CC_SHA256(keyData.bytes, (CC_LONG)keyData.length, digest);

NSData *out = [NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH];

    const unsigned char *buffer = (const unsigned char *)[out bytes];

    NSMutableString *HMAC = [NSMutableString stringWithCapacity:out.length * 2];

    for(inti =0; i

    [HMACappendFormat:@"%02x", buffer[i]];

    }

NSString* haSha = [HMAC uppercaseString];//如果后台将数据转化为大写，此处也应该转为大写

returnhaSha;

}

@end

-------------------------------------------------------------

如果是后台对key加密的话

#import <CommonCrypto/CommonDigest.h>

#import <CommonCrypto/CommonHMAC.H>

- (NSString *)hmac:(NSString *)plaintext withKey:(NSString *)key

{

const char *cKey  = [key cStringUsingEncoding:NSASCIIStringEncoding];

const char *cData = [plaintext cStringUsingEncoding:NSASCIIStringEncoding];

unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH];

CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC);

NSData *HMACData = [NSData dataWithBytes:cHMAC length:sizeof(cHMAC)];

const unsigned char *buffer = (const unsigned char *)[HMACData bytes];

NSMutableString *HMAC = [NSMutableString stringWithCapacity:HMACData.length * 2];

for (int i = 0; i < HMACData.length; ++i){

[HMAC appendFormat:@"%02x", buffer[i]];

}

return HMAC;

}