NSAttributedString添加文本对齐方式 [英] NSAttributedString add text alignment

问题描述

如何将文本对齐属性添加到NSAttributedString以使文本居中？

How can I add text alignment attribute to an NSAttributedString to center the text?

编辑：
我做错了什么？它似乎没有改变对齐。

Am I doing anything wrong? It doesn't seem to change the alignment.

CTParagraphStyleSetting setting;
setting.spec = kCTParagraphStyleSpecifierAlignment;
setting.valueSize = kCTCenterTextAlignment;

CTParagraphStyleSetting settings[1] = {
    {kCTParagraphStyleSpecifierAlignment, sizeof(CGFloat), &setting},           
};

CTParagraphStyleRef paragraph = CTParagraphStyleCreate(settings, sizeof(setting));

NSMutableAttributedString *mutableAttributed = [[NSMutableAttributedString alloc] initWithAttributedString:self.attributedString];
[mutableAttributed addAttributes:[NSDictionary dictionaryWithObjectsAndKeys:(NSObject*)paragraph ,(NSString*) kCTParagraphStyleAttributeName, nil] range:_selectedRange];

推荐答案

作为 NSAttributedString 主要用于iOS上的Core Text，你必须使用 CTParagraphStyle 而不是 NSParagraphStyle 。没有可变的变体。

As NSAttributedString is primarily used with Core Text on iOS, you have to use CTParagraphStyle instead of NSParagraphStyle. There is no mutable variant.

例如：

CTTextAlignment alignment = kCTCenterTextAlignment;

CTParagraphStyleSetting alignmentSetting;
alignmentSetting.spec = kCTParagraphStyleSpecifierAlignment;
alignmentSetting.valueSize = sizeof(CTTextAlignment);
alignmentSetting.value = &alignment;

CTParagraphStyleSetting settings[1] = {alignmentSetting};

size_t settingsCount = 1;
CTParagraphStyleRef paragraphRef = CTParagraphStyleCreate(settings, settingsCount);
NSDictionary *attributes = @{(__bridge id)kCTParagraphStyleAttributeName : (__bridge id)paragraphRef};
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:@"Hello World" attributes:attributes];

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