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绘图

（一）UIBezierPath

-画出坠落轨迹

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- (void)drawRect:(CGRect)rect {
    //draw a parabola with one point
    UIBezierPath *parabola_path = [UIBezierPath bezierPath];
    [parabola_path moveToPoint:CGPointMake(150, 40)];
    //加一个受力点
    [parabola_path addQuadCurveToPoint:CGPointMake(150, 140) controlPoint:CGPointMake(220, 65)];
    [parabola_path moveToPoint:CGPointMake(220, 65)];
    //[parabola_path addLineToPoint:CGPointMake(200, 65)];
     [[UIColor orangeColor]setStroke];
    parabola_path.lineWidth = 10;
    [parabola_path stroke];  
    //draw a parabol with more than one point
    UIBezierPath *sline_path = [UIBezierPath bezierPath];
    [sline_path moveToPoint:CGPointMake(150, 30)];
    //加两个受力点
    [sline_path addCurveToPoint:CGPointMake(150, 400) controlPoint1:CGPointMake(80,70) controlPoint2:CGPointMake(230, 160)];
    sline_path.lineWidth = 5;
    [sline_path stroke];
    //sline_path
}
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NSNotificationCenter

iOS通知中心

- NSNotification类

一个消息对象类,有三个成员变量

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@property (readonly, copy) NSString *name;
@property (readonly, retain) id object;
@property (readonly, copy) NSDictionary *userInfo;
  • name:辨别消息对象的唯一标识
  • object:针对某一个对象的消息
  • userInfo:用来传值的一个字典

- NSNotificationCenter类

通知中心,使用单例设计,每个应用程序都会有一个默认的通知中心.用于调度通知的发送和接受

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KVO

key Value Observer它提供一种机制，当指定的对象的属性被修改后，则对象就会接受到通知。简单的说就是每次指定的被观察的对象的属性被修改后，KVO就会自动通知相应的观察者了。

为想要观察的对象添加观察者

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[object addObserver:observer
        forKeyPath:@"frame"
        options:NSKeyValueObservingOptionNew
        context:nil];
  • object:被观察对象
  • observer:观察对象
  • forKeyPath:需要检测的属性(property的name),如UIViewV的frame,center
  • context:任意类型(一种标识,可用于同时监听不同对象的相同属性？)
    options:
  • options:
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NSKeyValueObservingOptionNew  更改前的值
NSKeyValueObservingOptionOld  更改后的值
NSKeyValueObservingOptionInitial 初始化的值,一旦注册,立马调用一次,通常会带有新值,不会带有旧值
NSKeyValueObservingOptionPrior 分两次调用,值改变之前和值改变后

添加观察键值变化的处理方法

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-(void)observeValueForKeyPath:(NSString *)keyPath
                     ofObject:(id)object
                     change:(NSDictionary<NSString *,id> *)change
                     context:(void *)context
}
@end
  • KeyPath:对应forKeyPath
  • object: 被观察者
  • change: 对应相应选项下值的改变(字典类型)可通过对应的key取值,key有new,old,等,可打印输出观察取key值
  • context: 对应context
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CA:CoreAnimation动画

属于CALayer层的动画,属于最底层,UIView的底层也是CALayer,UIView是基于CALayer的封装,CALayer具备UIView的所有属性和方法

1. CABasicAnimation

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CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.y"];
animation.toValue = @(M_PI*2);
animation.duration = 3;
animation.repeatCount = MAXFLOAT;
[_imageView.layer addAnimation:animation forKey:@"animationY"];
  1. key：addAnimation时的key,为自定义动画时的标识，可用于指定动画进行操作,比如删除指定动画
    key获取
  2. KeyPath：系统动画类型标识，用于获得系统动画
    • transform.rotation.x :系统绕x轴旋转动画
    • transform.rotation.y :系统绕y轴旋转动画
    • transform.rotation.z :系统绕z轴旋转动画
    • position : 用于CAKeyframeAnimation做沿“轨迹”运动,见下详细示例

2. CAKeyframeAnimation

CA帧动画,通常可用于按“轨迹”运动，与UIBezierPath结合

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UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:rect];
UIBezierPath *arc = [UIBezierPath bezierPathWithArcCenter:self.view.center radius:120 startAngle:M_PI_2*3 endAngle:M_PI_2*3+M_PI*2 clockwise:YES];
  //要沿着路劲跑，必须用关键帧动画
  //position:沿着路径动画
CAKeyframeAnimation *moveAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
  //设置动画的路径
moveAnimation.path = arc.CGPath;
moveAnimation.duration = 3;
moveAnimation.repeatCount = MAXFLOAT;
[_imageView.layer addAnimation:moveAnimation forKey:@"runWithPath"];
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CALayer

CAlayer是UIView的底层,通过修改CALayer去做一些界面的修改i

  • 发送通知
  • 接收通知
  • 删除通知