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.
在使用能够拉伸的图片时，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。
于是加入上获取上下文的代码例如以下：
UIGraphicsBeginImageContext(imageViewSeparate.frame.size);
imageViewSeparate.image = [[UIImageimageNamed:@"切割线拉伸.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(1.0,10.0, 1.0,10.0)];
UIGraphicsEndImageContext();