QQ去除未读状态的动画

- (void)drawRect:(CGRect)rect
{

    switch (_state) {

        case
SRSlimeStateNormal:

        {

            float percent =
1 -
distansBetween(_startPoint ,
_toPoint) /
_viscous;

            if (percent ==
1) {

                CGContextRef context =
UIGraphicsGetCurrentContext();

                UIBezierPath *path = [UIBezierPath
bezierPathWithRoundedRect:CGRectMake(_startPoint.x
- _radius,
_startPoint.y -
_radius,
2*_radius,
2*_radius)

                                                                cornerRadius:_radius];

                [self
setContext:context
path:path];

                CGContextDrawPath(context,
kCGPathFillStroke);

            }else {

                CGFloat startRadius =
_radius * (kStartTo + (1-kStartTo)*percent);

                CGFloat endRadius =
_radius * (kEndTo + (1-kEndTo)*percent);

                CGContextRef context =
UIGraphicsGetCurrentContext();

               

                UIBezierPath *path = [self
bodyPath:startRadius

                                                end:endRadius

                                            percent:percent];

                [self
setContext:context
path:path];

                CGContextDrawPath(context,
kCGPathFillStroke);

                if (percent <=
0) {

                    _state =
SRSlimeStateShortening;

                    [self
scaling];

                }

            }

        }

            break;

        case
SRSlimeStateShortening:

        {

            _toPoint =
CGPointMake((_toPoint.x
- _startPoint.x)*0.8
+ _startPoint.x,

                                       (_toPoint.y -
_startPoint.y)*0.8
+ _startPoint.y);

            float p =
distansBetween(_startPoint,
_toPoint) /
_viscous;

            float percent =1 -p;

            float r =
_radius * p;

           

            if (p >
0.01) {

                CGFloat startRadius = r * (kStartTo + (1-kStartTo)*percent);

                CGContextRef context =
UIGraphicsGetCurrentContext();

               

                CGFloat endRadius = r * (kEndTo + (1-kEndTo)*percent)
* (1+percent /
2);

                UIBezierPath *path = [self
bodyPath:startRadius

                                                end:endRadius

                                            percent:percent];

                [self
setContext:context
path:path];

                CGContextDrawPath(context,
kCGPathFillStroke);

            }else {

                self.hidden =
YES;

                _state =
SRSlimeStateMiss;

            }

        }

            break;

        default:

            break;

    }

}