ios - ios 6 和 ios 5.1 之间核心文本的差异？

Question

从这两个屏幕截图中可以看出，ios 5.1 和 ios 6 之间的 CoreText 实现似乎存在一些差异:

iOS 6:

iOS 5:

首先，文本颜色应用不正确。似乎在 ios 5.1 上，kCTForegroundColorAttributeName 要求您给它一个 CGColor，而在 ios 6 上，传递一个 UIColor 就足够了。所以我通过将代码更改为:

[attributes setObject:(id)[color CGColor] 
               forKey:(NSString*)kCTForegroundColorAttributeName];

其次，段落间距有点不对。 “sight”和“According”之间的距离是 11px vs 25px(在屏幕截图中测量)。在这两种情况下，段落间距都设置为 5:

NSMutableData *styleSettingsArray = [NSMutableData data];
CGFloat spaceBefore,spaceAfter;
...
CTParagraphStyleSetting styleSettingB = {kCTParagraphStyleSpecifierParagraphSpacingBefore   ,sizeof(CGFloat),&spaceBefore};
CTParagraphStyleSetting styleSettingA = {kCTParagraphStyleSpecifierParagraphSpacing         ,sizeof(CGFloat),&spaceAfter};
[styleSettingsArray appendBytes:&styleSettingB length:sizeof(styleSettingB)];
[styleSettingsArray appendBytes:&styleSettingA length:sizeof(styleSettingA)];
...
if(styleSettingsArray.length > 0)
{
    CTParagraphStyleRef paragraphStyleRef = CTParagraphStyleCreate([styleSettingsArray bytes], [styleSettingsArray length] / sizeof(CTParagraphStyleSetting));
    [dictionary setObject:(__bridge id)(paragraphStyleRef) forKey:(NSString*)kCTParagraphStyleAttributeName];
    CFRelease(paragraphStyleRef);
}

控制台中paragraphStyleRef的说明:

iOS 6:
CTParagraphStyle:
base writing direction = -1, alignment = 3, line break mode = 0, default tab interval = 0
first line head indent = 0, head indent = 0, tail indent = 0
line height multiple = 0, maximum line height = 0, minimum line height = 0
line spacing adjustment = 0, paragraph spacing = 5, paragraph spacing before = 5


iOS 5:

CTParagraphStyle:
writing direction = -1, alignment = 3, line break mode = 0, default tab interval = 0
first line head indent = 0, head indent = 0, tail indent = 0
line height multiple = 0, maximum line height = 0, minimum line height = 0
line spacing adjustment = 0, paragraph spacing = 5, paragraph spacing before = 5

这对我来说似乎是一样的，所以我不知道是什么问题。除了段落之间的间距外，它们是相同的。

那么我该如何解决这个问题呢？还有其他我应该注意的事情可能会导致文本显示不同吗？

编辑: 经过一番调查，原来段落样式的差异实际上是由我打印“\r\n”的换行符引起的。将其更改为“\n”解决了间距问题。

Answer 1

Core Text 在 iOS 6 中进行了彻底修改。如果您拥有 Apple 开发者帐户，可以免费观看 WWDC 2012 视频来查看所有更改。

所以现在在 iOS 6 中，您不能使用任何低级别的 Core Text 属性，例如 kCTForegroundColorAttributeName 或 kCTParagraphStyleAttributeName。

相反，您可以使用一组新的高级属性，例如 NSForegroundColorAttributeName 和 NSParagraphStyle。

因此您的代码将更改为:

/*Note that you have use the Foundation class
  for the attribute value instead of it's Core-Foundation counterpart.*/

[attributes setObject:color 
           forKey:NSForegroundColorAttributeName];

CGFloat spaceBefore, spaceAfter;

NSMutableParagraphStyle *mutableParagraphStyle = [NSMutableParagraphStyle defaultParagraphStyle];
mutableParagraphStyle.paragraphSpacing = spaceAfter;
mutableParagraphStyle.paragraphSpacingBefore = spaceBefore;

[attributes setObject:mutableParagraphStyle 
           forKey:NSParagraphStyleAttributeName];

您可以在此处找到所有新属性 的文档: http://developer.apple.com/library/ios/#documentation/uikit/reference/NSAttributedString_UIKit_Additions/Reference/Reference.html