How to encode and decode Files as Base64 in Cocoa

问题:

I am currently trying to get a small soap client to work, which includes to send a certificate file within the xml of the request.

I have no trouble getting the file into an NSData object - but then I have to convert it to some Base64 String. Environment is Mac OSX, Xcode 4.3.

I have found a lot of older posting dealing with that - but the best I found was some code that made use of OpenSSL libs and where containing loads of deprecated methods.

So, my question is as follows: Is there a better way than to use the OpenSSL libs? If yes, do you perchance have some URL or more recent code scraps?

If no, I guess there is some project out there which deals with Base64 that can be recommended. After all Base64 is not that uncommon.

Thanks for your help!

回答1:

Here is a base64 encoding done with CommonCrypto:

it is very easy code, it would not be difficult to put it in a category

if you add this to your project you need also to add the Security.framework

#include <CoreFoundation/CoreFoundation.h>
#include <Security/Security.h>

static NSData *base64helper(NSData *input, SecTransformRef transform)
{
    NSData *output = nil;

    if (!transform)
        return nil;

    if (SecTransformSetAttribute(transform, kSecTransformInputAttributeName, input, NULL))
        output = (NSData *)SecTransformExecute(transform, NULL);

    CFRelease(transform);

    return [output autorelease];
}

NSString *base64enc(NSData *input)
{
    SecTransformRef transform = SecEncodeTransformCreate(kSecBase64Encoding, NULL);

    return [[[NSString alloc] initWithData:base64helper(input, transform) encoding:NSASCIIStringEncoding] autorelease];
}

NSData *base64dec(NSString *input)
{
    SecTransformRef transform = SecDecodeTransformCreate(kSecBase64Encoding, NULL);

    return base64helper([input dataUsingEncoding:NSASCIIStringEncoding], transform);
}

回答2:

If you are using the iOS 7 or OS X 10.9 SDK, you can use the new base64 capabilities of NSData.

If you are using an older SDK, just add this declaration to get NSData base64 encoding and decoding. This will work on iOS 4+ and OS X 10.7+.

#ifndef __IPHONE_7_0
@interface NSData (NSDeprecated)
- (id)initWithBase64Encoding:(NSString *)base64String NS_DEPRECATED(10_6, 10_9, 4_0, 7_0);
- (NSString *)base64Encoding NS_DEPRECATED(10_6, 10_9, 4_0, 7_0);
@end
#endif

回答3:

Here is a simple NSData Base64 category I wrote. It uses the plist serialization/deserialization mechanism under the hood. Also, duping radar #9896929 would be nice.

回答4:

This works for OSX and it's ok using this with SDK's starting from 10.6 to 10.8. For 10.9 the methods have changed a bit (although at the time of writing, they work), but it's all documented on

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSData_Class/DeprecationAppendix/AppendixADeprecatedAPI.html#//apple_ref/occ/instm/NSData/base64Encoding

+ (NSString *) base64StringFromFileAtPath: (NSString*) filePath {
    NSData * dataFromFile = [NSData dataWithContentsOfFile:filePath];
    return [dataFromFile base64Encoding];
}


+ (NSData*) dataFrom64String : (NSString*) stringEncodedWithBase64
{
    NSData *dataFromBase64 = [[NSData alloc] initWithBase64Encoding:stringEncodedWithBase64];
    return dataFromBase64;
}