我在Stack Overflow上搜索了很多,但是我找不到解决方案.也许我只是误解了一些答案.
我创建了一个UITextView,我正在使用NSAttributedStrings来处理UITextView,这很好.
现在,添加自定义属性后,我被卡住了.
在哪里可以挂钩以在UITextView中呈现我的自定义属性?是否有委托方法,还是我必须创建自己的UITextView并覆盖方法?
最佳答案 您可以自定义NSLayoutManager,并实现它的-drawGlyphsForGlyphRange:atPoint:方法.
例如,您需要具有圆角半径的自定义背景
textView init:
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’有一个红色的圆形背景.