一种解决办法：CGContextSaveGState: invalid context 0x0

遇到这个问题找了好久答案，最后排错排出来了
CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability.
This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

在使用可以拉伸的图片时，希望保留圆角不被拉伸，使用了resizableImageWithCapInsets函数，可能是这个函数没有获取上下文才报的这个错。
于是添加上获取上下文的代码如下：
UIGraphicsBeginImageContext(imageViewSeparate.frame.size);
  imageViewSeparate.image = [[UIImageimageNamed:@"分割线拉伸.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(1.0,10.0,
1.0,10.0)];
UIGraphicsEndImageContext();