crash fix with iOS 7 stringByAddingPercentEncodingWithAllowedCharacters method

[sftnhrd]

No description provided.

[kcharwood]

Thanks @softenhard. This has been on my list to fix, but I hadn't yet thought about how to handle some of the double byte characters like emoji. I know relying on NSString length and enumeration can result in a split character. Any thoughts on that?

[sftnhrd]

@kcharwood Oh yes, forgot about that while fast-fixing my project :)
So I've added a couple of lines to support multibyte characters.
Check it out:

static NSUInteger const batchSize = 50;

    NSInteger index = 0;
    NSMutableString *escaped = @"".mutableCopy;

    while (index < string.length) {
        NSUInteger length = MIN(string.length - index, batchSize);
        NSRange range = NSMakeRange(index, length);

        // To avoid breaking up character sequences such as 👴🏿
        range = [string rangeOfComposedCharacterSequencesForRange:range];

        NSString *substring = [string substringWithRange:range];
        NSString *encoded = [substring stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];
        [escaped appendString:encoded];

        index += range.length;
    }

[kcharwood]

What happens if the split is on the mutlibyte character? Is the character included in both results?

Could you add some unit tests demonstrating the fix? Thanks!

[kcharwood]

Updated in 6b6d41d

[kcharwood]

Merged with 6b6d41d

[kcharwood]

Merged in 3_0_0 with 039a317

[Coeur]

As AFNetworking code is referencing this issue in https://github.com/AFNetworking/AFNetworking/blob/master/AFNetworking/AFURLRequestSerialization.m#L54, I'd like to quote in this pull request the details of this issue.

The reason and the workaround was discovered by @PrideChung and is a memory crash issue in stringByAddingPercentEncodingWithAllowedCharacters, reported in Alamofire/Alamofire#206. Scope of this issue was refined by @cnoon as only affecting iOS7 and iOS8, not affecting iOS9:

Batching is required for escaping due to an internal bug in iOS 8.1 and 8.2. Encoding more than a few hundred Chinese characters causes various malloc error crashes. To avoid this issue until iOS 8 is no longer supported, batching MUST be used for encoding. This introduces roughly a 20% overhead.

[CodeLife2012]

nice

[fighterLS]

I get a crash in my application. like this
| Application Specific Information: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString appendString:]: nil argument'
-- | --
0 | CoreFoundation | 0x0000000202a74ec4 ___exceptionPreprocess + 228
1 | libobjc.A.dylib | 0x0000000201c45a40 _objc_exception_throw + 56
2 | CoreFoundation | 0x000000020297b594 +[NSException raise:format:] + 116
3 | CoreFoundation | 0x00000002029ea7d8 _mutateError + 204
4 | homework | 0x0000000102ae95dc AFPercentEscapedStringFromString (AFURLRequestSerialization.m:73)
5 | homework | 0x0000000102ae9880 -[AFQueryStringPair URLEncodedStringValue] (AFURLRequestSerialization.m:108)
6 | homework | 0x0000000102ae9a8c AFQueryStringFromParameters (AFURLRequestSerialization.m:0)
7 | homework | 0x0000000102aec560 -[AFHTTPRequestSerializer requestBySerializingRequest:withParameters:error:] (AFURLRequestSerialization.m:0)
8 | homework | 0x0000000102aeb878 -[AFHTTPRequestSerializer requestWithMethod:URLString:parameters:error:] (AFURLRequestSerialization.m:376)