ios 柱圖和餅圖

餅圖：https://github.com/honcheng/iOSPlot

餅圖：https://github.com/tylerneylon/moriarty

柱圖：http://www.devdiv.com/iOS_iPhone-%E5%88%86%E4%BA%AB%E4%B8%80%E4%B8%AA%E5%88%AB%E4%BA%BA%E7%9A%84%E6%9F%B1%E5%9B%BE-thread-70067-1-1.html

日曆：https://github.com/klazuka/Kal

文字轉換：

CGContextSetFillColorWithColor(context,[UIColor blackColor].CGColor);                                    CGAffineTransform transform = CGAffineTransformIdentity;            transform = CGAffineTransformTranslate(transform, x, y); //A            transform = CGAffineTransformRotate(transform, - M_PI/6);      //B            transform = CGAffineTransformTranslate(transform, -x, -y);   //C                        //CGAffineTransform rotateTransform = CGAffineTransformMakeRotation(- M_PI/6);            CGContextSaveGState(context);            CGContextConcatCTM(context, transform);                                    [_lab.label drawAtPoint:CGPointMake(x,y) withFont:_font];                       CGContextRestoreGState(context);