UIView+TKCategory

 http://github.com/devinross/tapkulibrary

此框架是画图所用，方法如下：

// DRAW GRADIENT（画梯度）

+ (void) drawGradientInRect:(CGRect)rect withColors:(NSArray*)colors;

+ (void) drawLinearGradientInRect:(CGRect)rect colors:(CGFloat[])colors;

// DRAW ROUNDED RECTANGLE（画圆，长方形）

+ (void) drawRoundRectangleInRect:(CGRect)rect withRadius:(CGFloat)radius color:(UIColor*)color;

// DRAW LINE（画线）

+ (void) drawLineInRect:(CGRect)rect red:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)alpha;

+ (void) drawLineInRect:(CGRect)rect colors:(CGFloat[])colors;

+ (void) drawLineInRect:(CGRect)rect colors:(CGFloat[])colors width:(CGFloat)lineWidth cap:(CGLineCap)cap;