如何将选项卡停止添加到NSAttributedString并显示在UITextView中 [英] How do I add tab stops to an NSAttributedString and display in a UITextView

问题描述

我正在创建一个iOS应用，我想在UITextView中显示一个带有
特定制表位的属性字符串。我还想在drawRect中使用Core Text将
直接绘制到UIViews中。我希望（如果可能的话）
用于在两种情况下使用相同的属性字符串。

I'm creating an iOS app, and I would like to display an attributed string with specific tab stops specified in a UITextView. I would also like to draw them directly into UIViews using Core Text in drawRect. I would like (if possible) for the same attributed string to be used in both scenarios.

因此，在我的应用程序中，我创建了一个CFAttributedStringRef或者NSAttributedString和
将CTParagraphStyle属性应用于它。然后，我尝试在UITextView中显示
属性字符串，我得到如下所示的崩溃：

So, in my app, I create an CFAttributedStringRef or an NSAttributedString and apply a CTParagraphStyle attribute to it. Then, I attempt to display the attributed string in a UITextView and I get a crash like the following:

-[__NSCFType headIndent]: unrecognized selector sent to instance 0x7545080

po 0x7545080
$0 = 122966144 CTParagraphStyle:
base writing direction = -1, alignment = 4, 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 = 0, 
   paragraph spacing before = 0
tabs:
(
   "CTTextTab: location = 20, alignment = 0, options = (none)\n",
   "CTTextTab: location = 40, alignment = 0, options = (none)\n",
   "CTTextTab: location = 60, alignment = 0, options = (none)\n",
   "CTTextTab: location = 80, alignment = 0, options = (none)\n",
   "CTTextTab: location = 100, alignment = 0, options = (none)\n",
   "CTTextTab: location = 120, alignment = 0, options = (none)\n"
)

我明白发生了什么，但我想知道我是否有任何其他方式
做我想做的事情。 iOS上的NSMutableParagraphStyle没有tab
stop支持，但我注意到OS X上的NSMutableParagraphStyle确实具有
功能。这让我觉得iOS NSMutableParagraphStyle有一天可以支持
。

I understand what is going on, but I am wondering if I have any alternative way of doing what I'd like to. NSMutableParagraphStyle on iOS does not have tab stop support, yet I notice that NSMutableParagraphStyle on OS X does have this capability. This leads me to think that the iOS NSMutableParagraphStyle may one day support this.

同时，有没有办法将标签停止添加到CFAttributedStringRef或者
NSAttributedString还有UITextView显示吗？

In the meantime, is there way to add tab stops to a CFAttributedStringRef or an NSAttributedString and still have a UITextView display it?

有问题的来源是：

- (void)viewWillAppear:(BOOL)animated
{
   CFDictionaryRef attrs = (__bridge CFDictionaryRef) @{};
   CFAttributedStringRef a = CFAttributedStringCreate(
       kCFAllocatorDefault, CFSTR("a\tb\tc\td"), attrs);

   CFMutableAttributedStringRef attrStr;
   attrStr = CFAttributedStringCreateMutableCopy(
       kCFAllocatorDefault, CFAttributedStringGetLength(a), a);

   CFArrayRef tabStops = (__bridge CFArrayRef) @[
       (__bridge id) CTTextTabCreate(0, 20, NULL),
       (__bridge id) CTTextTabCreate(0, 40, NULL),
       (__bridge id) CTTextTabCreate(0, 60, NULL),
       (__bridge id) CTTextTabCreate(0, 80, NULL),
       (__bridge id) CTTextTabCreate(0, 100, NULL),
       (__bridge id) CTTextTabCreate(0, 120, NULL)];

   const CTParagraphStyleSetting paraSettings[] = {
       {kCTParagraphStyleSpecifierTabStops, sizeof(CFArrayRef), &tabStops},
   };

   CTParagraphStyleRef paraStyle = CTParagraphStyleCreate(
       paraSettings, 
       sizeof(paraSettings) / sizeof(CTParagraphStyleSetting));

   CFRange range = CFRangeMake(0, CFAttributedStringGetLength(attrStr));
   CFAttributedStringSetAttribute(
       attrStr, range, kCTParagraphStyleAttributeName, paraStyle);

   CFRelease(paraStyle);
   CFIndex i, count = CFArrayGetCount(tabStops);
   for (i = 0; i < count; i++) {
       CFRelease(CFArrayGetValueAtIndex(tabStops, i));
   }

   [[self textView] setAttributedText:
       (__bridge NSAttributedString *)(attrStr)];
}

推荐答案

在iOS 7中你可以做它是这样的：

In iOS 7 you can do it like this:

UIFont *font = [UIFont systemFontOfSize:18.0];
NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
NSInteger cnt;
CGFloat tabInterval = 72.0;
paragraphStyle.defaultTabInterval = tabInterval;
NSMutableArray *tabs = [NSMutableArray array];
for (cnt = 1; cnt < 13; cnt++) {    // Add 12 tab stops, at desired intervals...
    [tabs addObject:[[NSTextTab alloc] initWithTextAlignment:NSTextAlignmentLeft location:tabInterval * cnt options:nil]];
}
paragraphStyle.tabStops = tabs;
NSDictionary *attributes = @{ NSFontAttributeName: font, NSParagraphStyleAttributeName: paragraphStyle};

这篇关于如何将选项卡停止添加到NSAttributedString并显示在UITextView中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！