CAAnimation动画/CAAnimation Group

动画分隐式动画和显式动画

CAAnimatione采用了CAMediaTiming协议,可以调整时间,包括持续时间,速度,重复次数;采用了CAAction协议,可以通过响应动作的方式来显示动画.

CAAnimation的一些派生类:
CATransition 提供渐变效果:(推拉push效果,消退fade效果,揭开reveal效果)
CAAnimationGroup 允许多个动画同时播放
CABasicAnimation 提供了对单一动画的实现
CAKeyframeAnimation 关键桢动画,可以定义行动路线
CAConstraint 约束类,在布局管理器类中用它来设置属性
CAConstraintLayoutManager 约束布局管理器,是用来将多个CALayer进行布局的.各个CALayer是通过名称来区分,而布局属性是通过CAConstraint来设置的.
CATransaction 事务类,可以对多个layer的属性同时进行修改.它分隐式事务,和显式事务.

事务管理(Transactions)
事务分两种:
1.隐式事务(implicit transaction)
除显式事务外,任何对于CALayer属性的修改,都是隐式事务.这样的事务会在run-loop中被提交.
如:
theLayer.opacity = 0.0;
theLayer.zPosition = -200;
theLayer.position = CGPointMake(0.0, 0.0);

2.显式事务(explicit transaction)
a. 通过明确的调用begin,commit来提交动画.优点是可以同时修改多个Layer的属性.
如:
[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue
forKey:kCATransactionDisableActions];
[aLayer removeFromSuperlayer];
[CATransaction commit];

b.可以重置持续时间
可以在begin,commit对中临时修改动画持续时间.
[CATransaction begin]
[CATransaction setValue:[NSNumber numberWithFloat:10.0f]
forKey:kCATransactionAnimationDuration];
theLayer.zPosition = 200.0;
theLayer.opacity = 0.0;
[CATransaction commit];

c.事务可以嵌套.
如:
//第一层嵌套
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:2.0f]
forKey:kCATransactionAnimationDuration];
theLayer.position = CGPointMake(0.0, 0.0);
//第二层嵌套
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:5.0f]
forKey:kCATransactionAnimationDuration];
theLayer.zPosition = 200.0;
theLayer.opacity = 0.0;
[CATransaction commit];
[CATransaction commit];

布局管理器示例如下:
//创建和设置一个布局管理器
theLayer.layoutManager = [CAConstraintLayoutManager layoutManager];

//创建layerA
CALayer *layerA = [CALayer layer];
layerA.name = @”layerA”;

//设置layerA的中点位置等于超类的中点位置
[layerA addConstraint:[CAConstraint constraintWithAttribute:kCAConstraintMidY
relativeTo:@”superLayer”
attribute:kCAConstraintMidY]];

[layerA addConstraint:[CAConstraint constraintWithAttribute:kCAConstraintMidX
relativeTo:@”superLayer”
attribute:kCAConstraintMidX]];
[theLayer addSublayer:layerA];

//创建layerB
CALayer *layerB = [CALayer layer];
layerB.name = @”layerB”;

//设置layerB的宽度等于layerA的宽度
[layerA addConstraint:[CAConstraint constraintWithAttribute:kCAConstraintWidth
relativeTo:@”LayerA”
attribute:kCAConstraintWidth]];

[layerA addConstraint:[CAConstraint constraintWithAttribute:kCAConstraintMidX
relativeTo:@”layerA”
attribute:kCAConstraintMidX]];

[theLayer addSublayer:layerB];