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Emoji freezing my APP on TTTAttributedLabel.m #251

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digabriel opened this issue Jul 31, 2013 · 3 comments
Closed

Emoji freezing my APP on TTTAttributedLabel.m #251

digabriel opened this issue Jul 31, 2013 · 3 comments

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@digabriel
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Hi. First of all, thanks for TTTAttributedLabel. It is awesome.
I'm having some strange issue when trying to display emoji characters.

For instance, this text
screen shot 2013-07-31 at 11 11 38 am causes the app to freeze on line 312 of the .m file (self.framesetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)self.renderedAttributedText);)

I run the app using Activity Monitor from Instruments and the CPU load increases to 100% when reaching this point of the code, causing the app freezin. The strange thing is that the app does not crash.

Anyone experiencing the same issue?

Thanks!
@schlu
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schlu commented Aug 26, 2013

I think I figured this out and have a very small test case.

This Code works:

TTTAttributedLabel *linkLabel = [[TTTAttributedLabel alloc] initWithFrame:CGRectMake(0, 0, 200, 10)];
linkLabel.text = //Any Emoji Character
[linkLabel addLinkToURL:[NSURL URLWithString:@"http://google.com"] withRange:NSMakeRange(0,2)];
[linkLabel sizeToFit];

This code does not:

TTTAttributedLabel *linkLabel = [[TTTAttributedLabel alloc] initWithFrame:CGRectMake(0, 0, 200, 10)];
linkLabel.text = //Any Emoji Character
[linkLabel addLinkToURL:[NSURL URLWithString:@"http://google.com"] withRange:NSMakeRange(0,1)];
[linkLabel sizeToFit];

The difference is that you (and I) are trying to add a link to the middle of a unicode character. So in order to cover the entire emoji character your range needs to be adjusted. For each unicode character you need to add 1 to your length in your range.

I don't think it should just hang, but I suspect this might be a coretext issue, not TTTAttributedLabel issue.

@digabriel
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@schlu i think that this is exactly what is happen. But i don't think that just add 1 will fix the issue for all unicode characters.

Some unicode characters are called "Composed characters" and can have a length higher the 1. So, in other sections of my app, i'm using this custom category method (of NSString) to calculate the correct length of a string:

-(NSUInteger)numberOfComposedCharacterSequences{
    __block NSUInteger count = 0;
    [self enumerateSubstringsInRange:NSMakeRange(0, self.length)
                             options:NSStringEnumerationByComposedCharacterSequences
                          usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop){
                              count++;
                          }];
    return count;
}

You could try this out on your code. I'm not using more TTTAttributedLabel :)
If you confirm that this solves the issue, i think that this issue can be closed.

@schlu
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schlu commented Aug 27, 2013

Right, I misspoke when I said "unicode" characters. I really meant something else.

I am not sure what you would do with your method.

When I run it on the string @"asdf" I get a count of 4. When I run it on any single emoji character I get 1.

I am also doing linking in the middle strings. So the total number of composed characters isn't that helpful.

Your tip about composed characters was incredible for me though. I wrote a function that takes a range the server is providing and converts it to the range that I need to provide for the link in the label. I am sure there is a better name for this category method on NSString. I should note that this is a very inefficient method if you have long strings, my strings are limited to < 100 characters or so and it seems fine.

- (NSRange)stringRangeInComposedCharactersRange:(NSRange)composedCharactersRange {
    __block int composedCount = 0;
    [self enumerateSubstringsInRange:NSMakeRange(0, self.length)
                             options:NSStringEnumerationByComposedCharacterSequences
                          usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop){
                              composedCount++;
                          }];
    if (self.length == composedCount) {
        return composedCharactersRange;
    } else {
        NSMutableString *composedCharacterString = [NSMutableString string];
        __block int currentComposedCount = 0;
        [self enumerateSubstringsInRange:NSMakeRange(0, self.length)
                                 options:NSStringEnumerationByComposedCharacterSequences
                              usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop){
                                  if (currentComposedCount >= composedCharactersRange.location &&
                                      currentComposedCount < composedCharactersRange.location + composedCharactersRange.length) {
                                      [composedCharacterString appendString:[self substringWithRange:substringRange]];
                                  }
                                  currentComposedCount++;
                              }];
        return [self rangeOfString:composedCharacterString];
    }
}

I am fine closing this issue. I don't think it is an issue in the library. And there is a work around.

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@schlu @digabriel