CGContextSaveGState vs UIGraphicsPushContext
cgcontext, drawrect, ios, objective-c
Solution
`UIGraphicsPushContext(context)` pushes context onto a stack of CGContextRefs (making context the current drawing context), whereas `CGContextSaveGState(context)` pushes the current graphics state onto the stack of graphics states maintained by context. You should use UIGraphicsPushContext if you need to make a new CGContextRef the current drawing context, and you should use CGContextSaveGState when you're working with one graphics context and just want to save, for example: the current transform state, fill or stroke colors, etc.
Problem
There are two drawRect methods: ``` - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSaveGState(context); // do drawing here CGContextRestoreGState(context); } ``` And ``` - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); UIGraphicsPushContext(context); // do drawing here UIGraphicsPopContext(); } ``` UIGraphicsPushContext / UIGraphicsPopContext are from UIKit while CGContextSaveGState / CGContextRestoreGState are from CoreGraphics. Questions: What is the difference between those methods? Which one is better to use? Are there some examples of proving one method better than other and vise versa?