iOS实现贝塞尔曲线动画

本文实例为大家分享了ios实现贝塞尔曲线动画的具体代码，供大家参考，具体内容如下

效果如图：

仿美人相机，手势滑动隐藏顶部view。为了方便讲解，将屏幕分为几个区域，如图：

在拖动过程中：

1、拖动距离小于minmovedistance，贝赛尔曲线发生形变
2、拖动大于minmovedistance，整个view开始下移

在松开手时：

1、拖动距离小于minmovedistance，未发生位移，贝塞尔曲线恢复形变
2、拖动大于minmovedistance，小于mindisappeardistance，贝塞尔曲线恢复形变、位移回到初始位置。
3、拖动大于mindisappeardistance，向下移动隐藏view

一、根据y轴位移量确定贝塞尔路径

在拖动时曲线形变、松手时曲线恢复形变的时候都需要改变贝塞尔曲线，实际上是改变二阶贝塞尔曲线的控制点，因此写一个方法，根据传入的y轴位移量得到新的贝塞尔路径：

- (cgpathref)getpathwithmovedistance:(cgfloat)distance{

    uibezierpath *path = [uibezierpath bezierpath];
    cgpoint startpoint = cgpointmake(0, 0);
    cgpoint controlpoint = cgpointmake(self.bounds.size.width*0.5, 60+distance);
    cgpoint endpoint = cgpointmake(self.bounds.size.width, 0);

    [path movetopoint:startpoint];
    [path addquadcurvetopoint:endpoint controlpoint:controlpoint];

    [path addlinetopoint:cgpointmake(self.bounds.size.width, self.bounds.size.height)];
    [path addlinetopoint:cgpointmake(0, self.bounds.size.height)];

    return path.cgpath;
}

二、初始化图形

初始化的时候，可以根据上一步的方法，传入位移量0，获取贝塞尔路径，并将获得的路径赋给cashapelayer：

- (id)initwithframe:(cgrect)frame{
    if (self = [super initwithframe:frame]) {
        self.originy = frame.origin.y;
        [self setuplayer];
        [self addgesure];
    }
    return self;
}

- (void)setuplayer{
    self.toplinelayer = [cashapelayer layer];
    self.toplinelayer.fillcolor = colorfortheme.cgcolor;
    self.toplinelayer.strokecolor = colorfortheme.cgcolor;
    self.toplinelayer.path = [self getpathwithmovedistance:0];
    [self.layer addsublayer:self.toplinelayer];
}

三、添加手势

添加uipangesturerecognizer拖动手势，并处理手势拖动和结束拖动的事件。

拖动时：

1、拖动距离小于minmovedistance，只有贝赛尔曲线发生形变，调用步奏一中的方法。
2、拖动距离大于minmovedistance，整个view开始下移

结束拖动时：

调用revertformy:方法，传入当前在y轴上已经发生的位移量

- (void)addgesure{
    if (self.gesture == nil) {
        self.gesture = [[uipangesturerecognizer alloc] initwithtarget:self action:@selector(handlepan:)];
    }
    [self addgesturerecognizer:self.gesture];
}

- (void)handlepan:(uipangesturerecognizer *)gesture{
    cgfloat distancex = [gesture translationinview:self].x;
    cgfloat distancey = [gesture translationinview:self].y;

    if (abs(distancex) > abs(distancey)) {
        return;
    }
    //拖动过程
    if (gesture.state == uigesturerecognizerstatechanged) {
        nslog(@"%f",distancey);

        //移动少于minmovedistance，贝赛尔曲线形变
        if (distancey > 0 && distancey <= minmovedistance) {
            self.toplinelayer.path = [self getpathwithmovedistance:distancey];
        }
        //移动大于minmovedistance，整个view下移
        else if (distancey > minmovedistance) {
            self.frame = cgrectmake(0, self.originy+distancey-minmovedistance, self.bounds.size.width, self.bounds.size.height);
        }
    }
    //手势结束
    if (gesture.state == uigesturerecognizerstateended || gesture.state == uigesturerecognizerstatecancelled || gesture.state == uigesturerecognizerstatefailed) {
        [self removegesturerecognizer:self.gesture];
        [self revertformy:distancey];
    }
}

四、revertformy：恢复形变方法

根据传入的y轴上的位移量，实现不同的效果：

1、y小于minmovedistance，未发生位移，贝塞尔曲线恢复形变
2、y大于minmovedistance，小于mindisappeardistance，贝塞尔曲线恢复形变、位移回到初始位置。
3、y大于mindisappeardistance，向下移动隐藏view

//手势结束后恢复或隐藏
-(void)revertformy:(cgfloat)y{

    //y < 最小的隐藏位移距离，未发生位移，贝塞尔曲线恢复动画
    if (y < mindisappeardistance) {
        cakeyframeanimation *vibrate = [cakeyframeanimation animationwithkeypath:@"path"];
        vibrate.timingfunction = [camediatimingfunction functionwithname:kcamediatimingfunctioneasein];
        vibrate.values = @[
                           (id) [self getpathwithmovedistance:y],
                           (id) [self getpathwithmovedistance:-(y * 0.3)],
                           (id) [self getpathwithmovedistance:(y * 0.2)],
                           (id) [self getpathwithmovedistance:-(y * 0.15)],
                           (id) [self getpathwithmovedistance:(y * 0.1)],
                           (id) [self getpathwithmovedistance:-(y * 0.07)],
                           (id) [self getpathwithmovedistance:(y * 0.05)],
                           (id) [self getpathwithmovedistance:0.0]
                           ];
        vibrate.duration = 0.5;
        vibrate.removedoncompletion = no;
        vibrate.fillmode = kcafillmodeforwards;
        vibrate.delegate = self;
        [self.toplinelayer addanimation:vibrate forkey:nil];
    }

    //y > 最小位移距离，发生了位移
    if(y > minmovedistance){
        [uiview animatewithduration:0.3 animations:^{
            cgfloat endy;
            //向上恢复view
            if (y < mindisappeardistance) {
                endy = self.originy;
            }
            //向下隐藏view
            else{
                endy = screen_height;
            }
            self.frame = cgrectmake(0, endy, screen_width, self.frame.size.height);
        }];
    }
}

五、双击屏幕空白，消失的view从底部上移，恢复到初始位置

这个只是为了回到初始状态，根据实际需求实现。

//恢复到初始位置
- (void)comeback{
    if (self.frame.origin.y <= self.originy) {
        return;
    }

    [uiview animatewithduration:0.3 animations:^{
        self.frame = cgrectmake(0, self.originy, screen_width, self.frame.size.height);
    } completion:^(bool finished) {
        [self revertformy:10];
    }];
}

完整代码

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。