实现绘图功能 通过UISegmentedControl来选择不同颜色的画笔-Brush drawing functions UISegmentedControl to choose different colors

可调节画笔粗细和颜色，可撤销上一步操作或全部操作，具有橡皮擦功能，可以保存图画到本地相册。 -Demo a simple drawing tools, adjustable brush thickness and color can be revoked on the step of the operation or all of the operations with the eraser function, you can save the picture to the local albu

Objective-C实现的涂鸦板，可以选择不同颜色和不同粗细的画笔，支持清屏，回退和保存图片-Doodle board Objective-C to achieve, can choose different colors and different thickness of the brush, support screen, back off and save pictures