objective-c - 悬停可可下划线 - Objective-C

Question

我一直试图在悬停一个 NSTextField 时加下划线。我第一次尝试时发生的事情是文本带有下划线，但它位于前一个文本的顶部。再一次尝试，它变得越来越大胆。

-(void)mouseEntered:(NSEvent *)theEvent {
if (is_underlined)
    return;
is_underlined = YES;

//NSDictionary *attrsDictionary =   [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:NSUnderlineStyleSingle] forKey:NSUnderlineStyleAttributeName];
//NSMutableAttributedString * as =  [[NSMutableAttributedString alloc] initWithString:self.event.label
                                                         //         attributes:attrsDictionary];
//[as autorelease];
NSMutableAttributedString * as = [[[self attributedStringValue] mutableCopy] autorelease];
[as beginEditing];
[as addAttribute:NSUnderlineStyleAttributeName
           value:[NSNumber numberWithInt:NSUnderlineStyleSingle]
           range:[[[self window] fieldEditor:YES forObject:self] selectedRange]];

[as endEditing];
[self setAttributedStringValue:as];
}

-(void)mouseExited:(NSEvent *)theEvent {
    if (!is_underlined)
        return;
    is_underlined = NO;
   // self.stringValue = self.event.label;
    //[self setAttributedStringValue:nil];
    NSMutableAttributedString * as = [[[self attributedStringValue] mutableCopy] autorelease];
    [as beginEditing];
    [as removeAttribute:NSUnderlineStyleAttributeName range:[[[self window] fieldEditor:YES forObject:self] selectedRange]];
   // [as addAttribute:NSUnderlineStyleAttributeName
      //         value:[NSNumber numberWithInt:0]
     //          range:[[[self window] fieldEditor:YES forObject:self] selectedRange]];

    [as endEditing];
    [self setAttributedStringValue:as];
}

Answer 1

我认为我已经找到了答案——它不在于代码本身，而在于我正在构建的演示代码。作者在 drawRect 中实现了这些视图，这意味着每次绘制矩形时，都会在同一位置创建一个新的文本字段。