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我正在尝试使用颜色、字体、大小和对齐方式绘制自定义字符串。

我之前使用 NSMutableAttributedString 进行了所有工作，但看起来文本对齐仅适用于段落对齐，它仅适用于非可变版本的 NSString。

所以，我不得不将我以前的代码更改为：

    //Note : _name variables are provided by my GUI for text, size and font name.

    //Create the String ColorRef
    CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
    const CGFloat myColor[] = {_color.r/255.0, _color.g/255.0, _color.b/255.0, 1.0f};
    CGColorRef colorRef = CGColorCreate(rgb, myColor);

    //Setup paragraph Alignment Ref
    CTTextAlignment theAlignment = kCTCenterTextAlignment;
    CFIndex theNumberOfSettings = 1;
    CTParagraphStyleSetting theSettings[1] = {{ kCTParagraphStyleSpecifierAlignment, sizeof(CTTextAlignment), &theAlignment }};
    CTParagraphStyleRef theParagraphRef = CTParagraphStyleCreate(theSettings, theNumberOfSettings);

    //Prep Font
    NSDictionary *fontAttributes = [NSDictionary dictionaryWithObjectsAndKeys: _fontName, (NSString *)kCTFontFamilyNameAttribute,
                                    [NSNumber numberWithFloat:_fontSize], (NSString *)kCTFontSizeAttribute,
                                    nil];
    CTFontRef font = [self newFontWithAttributes:fontAttributes];

    //Prepare String Attributes
    NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys: (id)font, (NSString *)kCTFontAttributeName,
                                                [NSNumber numberWithFloat:_fontSize], (NSString *)kCTFontSizeAttribute,
                                                                 (id)theParagraphRef, (NSString*)kCTParagraphStyleAttributeName, 
                                                                            colorRef, (NSString *)kCTForegroundColorAttributeName, nil];

    //Create the Attributed String
    NSAttributedString *myString = [[NSAttributedString alloc] initWithString:_textString
                                                                   attributes: attributes];

但是文本对齐仍然不起作用。其他一切都很好，但文本保持在左侧对齐。

为什么 ？

EDIT : Each of my strings are created inside a class that is a subclass of CATextLayer. Each of those TextLayers are then added to a CALayer as sublayers. On updates I apply trasformation matrix on the sublayers and use setNeedsDisplay. This is how I display the text on screen. Maybe There's a reason here why the CTParagraphStyleRef set is not working ?

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1 回答 1

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I have no clues why the ParagraphStyle that I've set is not working, But I've found a solution that's working for me, so I'm posting it in case someone encounter similar problems :

  • My class is subclassing CATextLayer, which I think would've been important to mention in my question (my bad, I'll edit it).
  • Inside my CATextLayer class, I create the string using the code shown in my question.
  • Then I use the self.alignmentMode = kCAAlignmentCenter; to align the text the way I want.
  • Each string is then added to a CALAyer for display

I've also found this very good guide on AttributedStrings that helped me improving my code and finding this solution.

于 2011-11-21T16:07:05.047 回答