定时器画图

- (id)initWithFrame:(CGRect)frame {

self= [super initWithFrame:frame];

if(self) {

_movePoint= CGPointMake(10, 10);

_linePoint = CGPointMake(10, 10);

[NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(onTimer) userInfo:nil repeats:YES];

}

return self;

}

- (void)onTimer {

CGPoint movePoint =_movePoint;

movePoint.x += 10;

movePoint.y += 10;

_movePoint = movePoint;

CGPoint linePoint = _linePoint;

linePoint.x += 5;

linePoint.y += 20;

_linePoint = linePoint;

//调用drawRect方法重新绘制

[self setNeedsDisplay];

}

- (void)drawRect:(CGRect)rect {

[super drawRect:rect];

//创建画布获取当前画板

CGContextRefcontext = UIGraphicsGetCurrentContext();

CGContextSetLineWidth(context, 10);

CGContextSetRGBStrokeColor(context, 1, 1, 0, 1);

CGContextSetLineJoin(context,kCGLineJoinRound);

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

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

CGContextStrokePath(context);

}