在實現(xiàn)CGContextRef制圖的過程用，因為直接調(diào)用“[self drawRect:self.bounds]”出現(xiàn)啦如下錯誤：
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextBeginPath: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextSetLineWidth: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextSetLineCap: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextSetLineJoin: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextSetRGBStrokeColor: 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.
Nov 7 15:22:09 7777 PasswordDemo[15969] <Error>: CGContextMoveToPoint: 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.
??解決辦法：
其實在實現(xiàn)的制圖過程中，我們不需要直接調(diào)用“[self drawRect:self.bounds]”，只要調(diào)用“[self setNeedsDisplay]”即可。
