Question

我创建了一个NSMutableAttributedString，其对齐方式如下：

UIFont * font =  [UIFont systemFontOfSize:[UIFont labelFontSize]];
/// Make a copy of the default paragraph style
NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
/// Set line break mode
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
/// Set text alignment
paragraphStyle.alignment = alignmentForString(textString) ;//NSTextAlignmentLeft;//NSTextAlignmentRight;// NSTextAlignmentNatural;//  NSTextAlignmentLeft;

NSDictionary *messageDrawRectAttributesDictionary = @{
                        NSFontAttributeName: font,
                        NSParagraphStyleAttributeName: paragraphStyle,
                        NSForegroundColorAttributeName:[UIColor blackColor]
                        };

NSMutableAttributedString * mutalbleAttributedString = [[NSMutableAttributedString alloc] initWithString:textString attributes:messageDrawRectAttributesDictionary];

我想知道（以后在应用中使用）如何获得我在此字符串中设置的对齐方式。

我尝试了这段代码，却没有完全理解我在做什么：

NSRange range = NSMakeRange(0,mutalbleAttributedString.length-1);
NSDictionary * paraDic =[mutalbleAttributedString attribute:NSParagraphStyleAttributeName atIndex:0 longestEffectiveRange:&range inRange:range];

现在，我搜索了大量示例代码，并阅读了Apple文档。但没有运气。我得到空字典。

我唯一需要帮助的是，如果有人可以编写正确的代码，那么将返回对齐数据。

Answer 1

当您调用attribute:atIndex:longestEffectiveRange:inRange:时，返回值是请求的属性的值，而不是字典。另外，请勿为两个范围参数传递range。

您的代码应该是这样的：

NSRange range = NSMakeRange(0, mutalbleAttributedString.length);
NSParagraphStyle *paraStyle = [mutalbleAttributedString attribute:NSParagraphStyleAttributeName atIndex:0 longestEffectiveRange:NULL inRange:range];
NSTextAlignment alignment = paraStyle.alignment;

请注意以下更改：

请求的属性的正确返回值
设置range
为NULL传递longestEffectiveRange:，因为您不关心该值。

Answer 2

您可以从NSMutableAttributedString获取对齐方式，如下所示：

 NSRange range = NSMakeRange(0, mutableAttributedString.length);
 NSDictionary *attributes = [mutableAttributedString attributesAtIndex:0 effectiveRange:&range];
 NSMutableParagraphStyle *paragraphStyle = attributes[NSParagraphStyleAttributeName];
 NSTextAlignment alignment = paragraphStyle.alignment;

Answer 3

Swift 5 示例：

var effectiveRange = NSMakeRange(0, attributedString.length)
let currentParagraphStyle: NSParagraphStyle = attributedText?.attribute(NSAttributedString.Key.paragraphStyle, at: 0, effectiveRange: &effectiveRange) as! NSParagraphStyle
let align = currentParagraphStyle.alignment
let lineSpacing = currentParagraphStyle.lineSpacing
let newParagraphStyle = currentParagraphStyle.lineHeightMultiple

如何从NSMutableAttributeString获取NSParagraphStyleAttributeName？

3 个答案: