iosanimationWithKeyPath

animationWithKeyPath的值：

　 transform.scale = 比例轉換

transform.scale.x = 闊的比例轉換

transform.scale.y = 高的比例轉換

transform.rotation.z = 平面圖的旋轉

transform.translation.x

transform.translation.y

transform.translation.z

opacity = 透明度

margin

zPosition

backgroundColor 背景颜色

cornerRadius 圆角

borderWidth

bounds

contents

contentsRect

cornerRadius

frame

hidden

mask

masksToBounds

opacity

position

shadowColor

shadowOffset

shadowOpacity

shadowRadius

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Core Animation Programming Guide

Table of Contents

Introduction

Core Animation Basics

Setting Up Layer Objects

Animating Layer Content

Building a Layer Hierarchy

Advanced Animation Tricks

Changing a Layer’s Default Behavior

Improving Animation Performance

Appendix A: Layer Style Property Animations

Appendix B: Animatable Properties

Appendix C: Key-Value Coding Extensions

Revision History

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Key-Value Coding Extensions

Core Animation extends the

NSKeyValueCoding

protocol as it pertains to the

CAAnimation

and

CALayer

classes. This extension adds default values for some keys, expands wrapping conventions, and adds key path support for

CGPoint

,

CGRect

,

CGSize

, and

CATransform3D

types.

Key-Value Coding Compliant Container Classes

The

CAAnimation

and

CALayer

classes are key-value coding compliant container classes, which means that you can set values for arbitrary keys. Even if the key

someKey

is not a declared property of the

CALayer

class, you can still set a value for it as follows:

[theLayer setValue:[NSNumber numberWithInteger:50] forKey:@"someKey"];

You can also retrieve the value for arbitrary keys like you would retrieve the value for other key paths. For example, to retrieve the value of the

someKey

path set previously, you would use the following code:

someKeyValue=[theLayer valueForKey:@"someKey"];

OS X Note: The

CAAnimation

and

CALayer

classes, which automatically archive any additional keys that you set up for instances of those classes, support the

NSCoding

protocol.

Default Value Support

Core Animation adds a convention to key value coding whereby a class can provide a default value for a key that has no set value. The

CAAnimation

and

CALayer

classes support this convention using the

defaultValueForKey:

class method.

To provide a default value for a key, create a subclass of the desired class and override its

defaultValueForKey:

method. Your implementation of this method should examine the key parameter and return the appropriate default value. Listing C-1 shows a sample implementation of the

defaultValueForKey:

method for a layer object that provides a default value for the

masksToBounds

property.

Listing C-1 Example implementation of defaultValueForKey:

+ (id)defaultValueForKey:(NSString *)key

{

if ([key isEqualToString:@"masksToBounds"])

return [NSNumber numberWithBool:YES];

return [super defaultValueForKey:key];

}

Wrapping Conventions

When the data for a key consists of a scalar value or C data structure, you must wrap that type in an object before assigning it to the layer. Similarly, when accessing that type, you must retrieve an object and then unwrap the appropriate values using the extensions to the appropriate class. Table C-1 lists the C types commonly used and the Objective-C class you use to wrap them.

Table C-1 Wrapper classes for C types

C type	Wrapping class
CGPoint	NSValue
CGSize	NSValue
CGRect	NSValue
CATransform3D	NSValue
CGAffineTransform	NSAffineTransform (OS X only)

Key Path Support for Structures

The

CAAnimation

and

CALayer

classes lets you access the fields of selected data structures using key paths. This feature is a convenient way to specify the field of a data structure that you want to animate. You can also use these conventions in conjunction with the

setValue:forKeyPath:

and

valueForKeyPath:

methods to set and get those fields.

CATransform3D Key Paths

You can use the enhanced key path support to retrieve specific transformation values for a property that contains a

CATransform3D

data type. To specify the full key path for a layer’s transforms, you would use the string value

transform

or

sublayerTransform

followed by one of the field key paths in Table C-2. For example, to specify a rotation factor around the layer’s z axis, you would specify the key path

transform.rotation.z

.

Table C-2 Transform field value key paths

Field Key Path	Description
rotation.x	Set to an NSNumber object whose value is the rotation, in radians, in the x axis.
rotation.y	Set to an NSNumber object whose value is the rotation, in radians, in the y axis.
rotation.z	Set to an NSNumber object whose value is the rotation, in radians, in the z axis.
rotation	Set to an NSNumber object whose value is the rotation, in radians, in the z axis. This field is identical to setting the rotation.z field.
scale.x	Set to an NSNumber object whose value is the scale factor for the x axis.
scale.y	Set to an NSNumber object whose value is the scale factor for the y axis.
scale.z	Set to an NSNumber object whose value is the scale factor for the z axis.
scale	Set to an NSNumber object whose value is the average of all three scale factors.
translation.x	Set to an NSNumber object whose value is the translation factor along the x axis.
translation.y	Set to an NSNumber object whose value is the translation factor along the y axis.
translation.z	Set to an NSNumber object whose value is the translation factor along the z axis.
translation	Set to an NSValue object containing an NSSize or CGSize data type. That data type indicates the amount to translate in the x and y axis.

The following example shows how you can modify a layer using the

setValue:forKeyPath:

method. The example sets the translation factor for the x axis to 10 points, causing the layer to shift by that amount along the indicated axis.

[myLayer setValue:[NSNumber numberWithFloat:10.0] forKeyPath:@"transform.translation.x"];

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