Core Graghics

//UIView需要重绘的时候调用setNeedDisplay即可

//drawRect负责UIView的展示》

// Only override drawRect: if you perform custom drawing.

// An empty implementation adversely affects performance during animation.

- (void)drawRect:(CGRect)rect

{

    //填充

    CGContextRef context = UIGraphicsGetCurrentContext();

    UIColor *grayColor = [UIColor grayColor];

    CGContextSetFillColorWithColor(context, grayColor.CGColor);

    CGContextFillRect(context, rect);

    //设置渐变色

    CGColorSpaceRef spaceRef = CGColorSpaceCreateDeviceRGB();

    NSArray *colors = @[(__bridge id)[UIColor redColor].CGColor,(__bridge id)[UIColor blueColor ].CGColor];

    CGFloat locations[] = {0,1};

    CGGradientRef gradientRef = CGGradientCreateWithColors(spaceRef, (__bridge CFArrayRef)(colors), locations);

    CGPoint start = rect.origin;

    CGPoint end = CGPointMake(rect.origin.x , rect.origin.y+rect.size.height);

    CGContextDrawLinearGradient(context, gradientRef, start, end, 0);

    CGGradientRelease(gradientRef);

    CGColorSpaceRelease(spaceRef);

    //设置线条

    CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor);

    CGContextSetLineWidth(context, 5);

    CGContextMoveToPoint(context, start.x, start.y);

    CGContextAddLineToPoint(context, end.x, end.y);

    CGContextStrokePath(context);

    //设置边框

    CGRect tempRect = CGRectInset(rect, 5, 5);

    CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);

    CGContextSetLineWidth(context, 5);

    CGContextStrokeRect(context, tempRect);

}