UITextView，NSAttributedString和自定义属性

Question

我在堆栈溢出方面进行了很多搜索，但找不到解决方案。也许我只是误解了一些答案。

我创建了一个，UITextView并且正在使用NSAttributedStringsUITextView很好。

现在，添加自定义属性后，我陷入了困境。

在哪里可以显示我的自定义属性UITextView？有委托方法，还是我必须创建自己UITextView的方法并覆盖方法？

Answer 1

您可以自定义NSLayoutManager，并实现它的-drawGlyphsForGlyphRange:atPoint:方法。

例如，您想要一个具有拐角半径的自定义背景

textView初始化：

NSTextStorage *textStorage = [NSTextStorage new];
CustomLayoutManager *layoutManager = [[CustomLayoutManager alloc] init];
CGSize containerSize = CGSizeMake(self.view.bounds.size.width,  CGFLOAT_MAX);
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:containerSize];

textContainer.widthTracksTextView = YES;
[layoutManager addTextContainer:textContainer];
[textStorage addLayoutManager:layoutManager];

self.textView = [[UITextView alloc] initWithFrame:yourFrame textContainer:textContainer];

并应用您的自定义属性：

NSMutableAttributedString *mAttrStr = [[NSMutableAttributedString alloc] initWithString:@"SampleText"];
[mAttrStr addAttribute:YourCustomAttributeName value:[UIColor redColor] range:NSMakeRange(0, mAttrStr.length)];  //for example, you want a custom background with a corner radius
[self.textView.textStorage appendAttributedString:mAttrStr];

在CustomLayoutManager.m中

-(void)drawGlyphsForGlyphRange:(NSRange)glyphsToShow atPoint:(CGPoint)origin {
    NSRange range = [self characterRangeForGlyphRange:glyphsToShow
                                 actualGlyphRange:NULL];
    //enumerate custom attribute in the range
    [self.textStorage enumerateAttribute:YourCustomAttributeName inRange:range options:NSAttributedStringEnumerationLongestEffectiveRangeNotRequired usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
        if (value) {
            UIColor *color = value; //the color set above

            NSRange glyphRange = [self glyphRangeForCharacterRange:range
                                          actualCharacterRange:NULL];
            NSTextContainer *container = [self textContainerForGlyphAtIndex:glyphRange.location
                                        effectiveRange:NULL];

            //draw background
            CGContextRef context = UIGraphicsGetCurrentContext();
            CGContextSaveGState(context);
            CGContextTranslateCTM(context, origin.x, origin.y);
            [color setFill];
            CGRect rect = [self boundingRectForGlyphRange:glyphRange inTextContainer:container];

            //UIBezierPath with rounded
            UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:100];
            [path fill];
            CGContextRestoreGState(context);
            //end draw

            [super drawGlyphsForGlyphRange:range atPoint:origin];
        }
        else {
            [super drawGlyphsForGlyphRange:range atPoint:origin];
        }

    }];
}

现在，“ SampleText”具有红色的圆形背景。