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HTML5 发布时间：2022-04-27 发布网站：大佬教程 code.js-code.com

大佬教程收集整理的这篇文章主要介绍了ios – 如何使NSStringDrawingContext缩小文本？，大佬教程大佬觉得挺不错的，现在分享给大家，也给大家做个参考。

我正在尝试使用iOS 6的归属字符串API来计算文本的大小,并在必要时缩小字体大小.但是,如文档所述,我无法使其正常工作.

NSString *String = @"This is a long text that doesn't shrink as it should";

NSStringDrawingContext *context = [NSStringDrawingContext new];
context.minimumScaleFactor = 0.5;

UIFont *font = [UIFont fontWithName:@"sourceSansPro-Bold" size:32.f];

NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
paragraphStyle.lineBreakmode = NSLineBreakByClipping;

NSDictionary *attributes = @{ NSFontAttributename: font,NSParagraphStyleAttributename: paragraphStyle };

NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:self.title attributes:attributes];

CGRect rect = [attributedString boundingRectWithSize:CGSizeMake(512.f,512.f) options:NSStringDrawingUsesLineFragmentOrigin context:context];

NSLog(@"rect: %@,context: %@",NSStringFromCGRect(rect),context.debugDescription);

但文本不缩小并被截断. actualScaleFactor始终为1.日志结果为：

rect:{{0,0},{431.64801,80.447998}},context:<NSStringDrawingContext: 0x14e85770> minimumScaleFactor:0.500000 minimumTrackingAdjustment:0.000000 actualScaleFactor:1.000000 actualTrackingAdjustment:0.000000 @R_601_10586@lBounds:{{0,80.447998}}

如果我使用实际的绘图方法而不是测量方法,结果是一样的.如果我删除段落样式,它会使文本包装并且不缩小.如果我删除段落样式,我选择一个只允许一行文本的大小,文本也被截断,而不是缩小.哪里不对？有很少的文档或在线资源处理NSStringDrawingContext.而且我试图避免使用sizeWithFont：minFontSize：actualFontSize：forWidth：lineBreakmode：在iOS 7中已被弃用.

解决方法@H_801_12@

NSStringDrawingContext的minimumScaleFactor在iOS 7中显示为破坏.

就我可以做出来,即使在iOS 6中,它也无法画画;它有助于测量,所以你可以解决在它像绘图一样工作的上下文中会发生什么,如UILabel.这样,你知道标签的正确最小高度.

或者,您可以使用生成的比例因子来缩小文本,这在现在知道它将适合.

例：

- (void)drawRect:(CGRect)rect
{
    // rect is 0,210,31

    NSMutableAttributedString* s = 
        [[NSMutableAttributedString alloc] initWithString: @"This is the army Mister Jones."];
    [s addAttributes:@{NSFontAttributename:[UIFont fontWithName:@"GillSans" size:20]} 
        range:NsmakeRange(0,s.length)];

    NSMutableParagraphStyle* para = [[NSMutableParagraphStyle alloc] init];
    para.lineBreakmode = NSLineBreakByTruncaTingTail;
    [s addAttributes:@{NSParagraphStyleAttributename:para} 
        range:NsmakeRange(0,s.length)];

    NSStringDrawingContext* con = [[NSStringDrawingContext alloc] init];
    con.minimumScaleFactor = 0.5;

    CGRect result = 
        [s boundingRectWithSize:rect.size 
            options:NSStringDrawingUsesLineFragmentOrigin context:con];
    CGFloat scale = con.actualScaleFactor;
    // ...(Could have a check here to see if result fits in target rect)...

    // fix font to use scale factor,and draw
    [s addAttributes:@{NSFontAttributename:[UIFont fontWithName:@"GillSans" size:20*scale]} 
        range:NsmakeRange(0,s.length)];
    [s drawWithRect:rect options:NSStringDrawingUsesLineFragmentOrigin context:nil];

}