Smooth line UIView

based on https://github.com/levinunnink/Smooth-Line-View

I add new function: 
1. undo
2. redo
3. clear
4. eraser
5. change color
6. save image to file
7. save image to album
8. load image from album

Usage

//Smooth Line View-Prefix.pch

//switch UIBezierPath / CGContext
#define USEUIBezierPath 0
//switch Image push to memory or files
#define PUSHTOFILE      1

Screenshots