Question

我试图创建一个UIButton的子类来强制执行文本字距调整。因此，当我在Interface Builder中构建一个按钮时，设置文本颜色（使用纯文本）我希望能够从普通{{1}中获取现有的文本，颜色，段落样式和字体。实例并将其转换为具有相同属性的属性标签。

我写了两个我认为可能有帮助的类别：

titleLabel

然后在我的UIButton子类中，我会像这样覆盖这些：

+ (NSMutableAttributedString*)attributedStringWithTitle:(NSString*)title fromExistingAttributedString:(NSAttributedString*)attributedString
{
    NSDictionary *attributes = [attributedString attributesAtIndex:0 effectiveRange:NULL];
    return [[NSMutableAttributedString alloc] initWithString:title attributes:attributes];
}

+ (NSMutableAttributedString*)attributedStringWithTitle:(NSString*)title fromPlainTextLabel:(UILabel*)label
{
    NSMutableAttributedString* mutableTitle = [[NSMutableAttributedString alloc] initWithString:title];
    [mutableTitle addAttribute:NSFontAttributeName value:label.font range:[mutableTitle fullRange]];
    [mutableTitle addAttribute:NSForegroundColorAttributeName value:label.textColor range:[mutableTitle fullRange]];
    NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    style.alignment = label.textAlignment;
    [mutableTitle addAttribute:NSParagraphStyleAttributeName value:style range:[mutableTitle fullRange]];
    return mutableTitle;
}

但是有些东西没有用 - 特别值得注意的是，- (void)setAttributedTitle:(NSAttributedString *)title forState:(UIControlState)state { NSMutableAttributedString* mutableTitle = [title mutableCopy]; [mutableTitle addAttributes:@{NSKernAttributeName: @(kDefaultKerning)} range:[mutableTitle fullRange]]; [super setAttributedTitle:mutableTitle forState:state]; [self setNeedsDisplay]; } - (void)setTitle:(NSString *)title forState:(UIControlState)state { NSMutableAttributedString* mutableTitle; if ([self attributedTitleForState:state]) { mutableTitle = [NSMutableAttributedString attributedStringWithTitle:title fromExistingAttributedString:[self attributedTitleForState:state]]; } else { mutableTitle = [NSMutableAttributedString attributedStringWithTitle:title fromPlainTextLabel:self.titleLabel]; } [self setAttributedTitle:mutableTitle forState:state]; }和[self attributedTitleForState:state]似乎总是零。在我看来，在Interface Builder中设置属性的方式存在一些脱节，因为当文本通过OK时，所有样式都缺失了。

Answer 1

终于有了这个工作。事实证明，纯文本UIButton有几个属性在几个地方。有些方法有直接从UIButton检索的辅助方法，有些方法没有。

字体：self.titleLabel.font（没有辅助方法）
颜色：[self titleColorForState:state]
文字：[self titleForState:state]
归属文字：[self attributedTitleForState]

默认情况下，纯文本UIButton没有任何文本对齐方式，因为那是controlled by content horizontal alignment。

因此，我改变了我的助手方法（第一个是相同的，但我不得不改变第二个）：

+ (NSMutableAttributedString*)attributedStringWithTitle:(NSString*)title fromExistingAttributedString:(NSAttributedString*)attributedString
{
    NSDictionary *attributes = [attributedString attributesAtIndex:0 effectiveRange:NULL];
    return [[NSMutableAttributedString alloc] initWithString:title attributes:attributes];
}

+ (NSMutableAttributedString*)attributedStringWithTitle:(NSString*)title font:(UIFont*)font color:(UIColor*)color 
{
    NSMutableAttributedString* mutableTitle = [[NSMutableAttributedString alloc] initWithString:title];
    [mutableTitle addAttribute:NSFontAttributeName value:font range:[mutableTitle fullRange]];
    [mutableTitle addAttribute:NSForegroundColorAttributeName value:color range:[mutableTitle fullRange]];
    NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    [mutableTitle addAttribute:NSParagraphStyleAttributeName value:style range:[mutableTitle fullRange]];
    return mutableTitle;
}

我已经像这样实现了它：

- (void)setAttributedTitle:(NSAttributedString *)title forState:(UIControlState)state
{
    NSMutableAttributedString* mutableTitle = [title mutableCopy];
    [mutableTitle addAttributes:@{NSKernAttributeName: @(kDefaultKerning)} range:[mutableTitle fullRange]];
    [super setAttributedTitle:mutableTitle forState:state];
    [self setNeedsDisplay];
}

- (void)setTitle:(NSString *)title forState:(UIControlState)state
{
    NSMutableAttributedString* mutableTitle;
    if ([self attributedTitleForState:state]) {
        mutableTitle = [NSMutableAttributedString attributedStringWithTitle:title fromExistingAttributedString:[self attributedTitleForState:state]];
    } else {
        mutableTitle = [NSMutableAttributedString attributedStringWithTitle:title font:self.titleLabel.font color:[self titleColorForState:state]];
    }
    [self setAttributedTitle:mutableTitle forState:state];
}

根据其原始纯文本状态创建UIButton属性标题

1 个答案: