问题描述
我正在尝试在UISlider中将拇指放在拇指上方的另一个UIView。为此，我需要拇指图像的宽度。在iOS6中，这很好用。我可以使用：
I'm trying to position an additional UIView centered above the thumb in a UISlider. To do this, I need the width of the thumb image. In iOS6, this works fine. I can use:
CGFloat thumbWidth = self.navSlider.currentThumbImage.size.width;
（如答案所示：）
这在iOS7中返回0.0f。我也试过用它来阅读：
This returns 0.0f in iOS7. I've also tried reading it using:
UIImage *thumb = [self.navSlider thumbImageForState:UIControlStateNormal];
但拇指最终为零。
是否可以读取默认滑块拇指图像的大小？或者我必须找到它，设置一个常量，以及Apple如何在以后不改变它？
Is it possible to read the size of the default slider thumb image? Or will I have to find it, set a constant, and how Apple doesn't change it later?
推荐答案
关于 currentThumbImage 属性说：
<$>上的文档c $ c> thumbImageForState：不太清楚：
我想你可能是运气不佳试图找出默认的拇指大小。如何安装看起来与系统映像完全相同的自定义拇指图像？这样就可以解决苹果公司从你身下改掉它的问题。
I think you might be out of luck trying to figure out the default thumb size. How about installing a "custom" thumb image that looks exactly like the system image? That would solve the problem of Apple changing it out from under you.
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