iphone ios layer 教程应用

CALayer(层)是屏幕上的一个矩形区域，在每一个UIView中都包含一个根CALayer，在UIView上的所有视觉效果都是在这个Layer上进行的。

CALayer外形特征主要包括：

1、层的大小尺寸

2、背景色

3、内容（可以填充图片或者使用Core Graphics绘制的内容）

4、矩形是否使用圆角

5、矩形是否有阴影

Layer有很多种，最常用也是最基本的是CALayer，当然还包括其他的子类：

CAScrollerLayer 简化显示层的一部分

CATextLayer 文本层

CAGradientLayer、CAShapeLayer等等

使用层之前，需要在项目中引入QuartzCore.framework框架

实例：

新建XCode项目LayerSample，导入QuartzCore.famework





在LayerSampleViewController.h文件中引入：

view plaincopy to clipboard#import <QuartzCore/QuartzCore.h>  
LayerSampleViewController.m文件，代码：  
//  
//  LayerSampleViewController.m  
//  LayerSample  
//  
//  Created by jordy on 11-3-28.  
//  Copyright 2011 vsp. All rights reserved.  
//  
  
#import "LayerSampleViewController.h"  
  
@implementation LayerSampleViewController  
  
// Implement loadView to create a view hierarchy programmatically, without using a nib.  
- (void)loadView {  
    UIView *rootView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];  
    rootView.backgroundColor = [UIColor whiteColor];  
    self.view = rootView;  
    [rootView release];  
  
    //加载layer  
  
    backLayer = [CALayer layer];  
    backLayer.backgroundColor = [UIColor orangeColor].CGColor;  
    backLayer.bounds = CGRectMake(10, 10, 1004, 728); //设置layer的区域  
    backLayer.position = CGPointMake(1024/2, 768/2-10); //设置layer坐标  
    [self.view.layer addSublayer:backLayer];  
  
}  
  
// Override to allow orientations other than the default portrait orientation.  
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {  
    return interfaceOrientation == UIInterfaceOrientationLandscapeLeft;  
}  
  
- (void)didReceiveMemoryWarning {  
    // Releases the view if it doesn't have a superview.  
    [super didReceiveMemoryWarning];  
  
    // Release any cached data, images, etc that aren't in use.  
}  
  
- (void)viewDidUnload {  
    // Release any retained subviews of the main view.  
    // e.g. self.myOutlet = nil;  
}  
  
- (void)dealloc {  
    [super dealloc];  
}  
  
@end  
[html] view plaincopy#import <QuartzCore/QuartzCore.h>  
LayerSampleViewController.m文件，代码：  
//  
//  LayerSampleViewController.m  
//  LayerSample  
//  
//  Created by jordy on 11-3-28.  
//  Copyright 2011 vsp. All rights reserved.  
//  
  
#import "LayerSampleViewController.h"  
  
@implementation LayerSampleViewController  
  
// Implement loadView to create a view hierarchy programmatically, without using a nib.  
- (void)loadView {  
    UIView *rootView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];  
    rootView.backgroundColor = [UIColor whiteColor];  
    self.view = rootView;  
    [rootView release];  
  
    //加载layer  
  
    backLayer = [CALayer layer];  
    backLayer.backgroundColor = [UIColor orangeColor].CGColor;  
    backLayer.bounds = CGRectMake(10, 10, 1004, 728); //设置layer的区域  
    backLayer.position = CGPointMake(1024/2, 768/2-10); //设置layer坐标  
    [self.view.layer addSublayer:backLayer];  
  
}  
  
// Override to allow orientations other than the default portrait orientation.  
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {  
    return interfaceOrientation == UIInterfaceOrientationLandscapeLeft;  
}  
  
- (void)didReceiveMemoryWarning {  
    // Releases the view if it doesn't have a superview.  
    [super didReceiveMemoryWarning];  
  
    // Release any cached data, images, etc that aren't in use.  
}  
  
- (void)viewDidUnload {  
    // Release any retained subviews of the main view.  
    // e.g. self.myOutlet = nil;  
}  
  
- (void)dealloc {  
    [super dealloc];  
}  
  
@end

运行程序：





为了区分背景UIView，我将UIView的背景色设置为白色，backLayer的背景色设置为橘***。

上图是一个矩形区域，如果设置矩形的四个角是椭圆角，可以添加属性：

backLayer.cornerRadius = 20.0; //矩形椭圆角的弧度半径

运行程序后，效果如图：





添加带阴影的子Layer（层）,代码：

view plaincopy to clipboard //添加子layer  
CALayer *cyanLayer = [CALayer layer];  
cyanLayer.backgroundColor = [UIColor cyanColor].CGColor;  
cyanLayer.bounds = CGRectMake(0, 0, 300, 300);  
cyanLayer.position = CGPointMake(180, 180);  
cyanLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量  
cyanLayer.shadowRadius = 10.0;  //设置阴影的半径  
cyanLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色  
cyanLayer.shadowOpacity = 0.9; //设置阴影的不透明度  
  
[backLayer addSublayer:cyanLayer];  
[html] view plaincopy //添加子layer  
CALayer *cyanLayer = [CALayer layer];  
cyanLayer.backgroundColor = [UIColor cyanColor].CGColor;  
cyanLayer.bounds = CGRectMake(0, 0, 300, 300);  
cyanLayer.position = CGPointMake(180, 180);  
cyanLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量  
cyanLayer.shadowRadius = 10.0;  //设置阴影的半径  
cyanLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色  
cyanLayer.shadowOpacity = 0.9; //设置阴影的不透明度  
  
[backLayer addSublayer:cyanLayer];

运行效果图：





给子Layer添加图片

view
plaincopy
to clipboard

//添加子image layer

UIImage *image =
[UIImage imageNamed:@"feiche.jpg"];

CALayer *imageLayer =
[CALayer layer];

imageLayer.frame = CGRectMake(100,
100, image.size.width, image.size.height);

imageLayer.contents =
(id) image.CGImage;

imageLayer.shadowOffset = CGSizeMake(0,
3); //设置阴影的偏移量

imageLayer.shadowRadius = 10.0;
//设置阴影的半径

imageLayer.shadowColor =
[UIColor blackColor].CGColor; //设置阴影的颜色为黑色

imageLayer.shadowOpacity = 0.9;
//设置阴影的不透明度

[backLayer addSublayer:imageLayer];

[html] view
plaincopy

//添加子image layer

UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

CALayer *imageLayer = [CALayer layer];

imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

imageLayer.contents = (id) image.CGImage;

imageLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量

imageLayer.shadowRadius = 10.0; //设置阴影的半径

imageLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

imageLayer.shadowOpacity = 0.9; //设置阴影的不透明度



[backLayer addSublayer:imageLayer];

运行效果，





图片加边框，代码：

view plaincopy to clipboardimageLayer.borderColor = [UIColor grayColor].CGColor;  //边框颜色  
imageLayer.borderWidth = 2.0;  //边框宽度  
[html] view plaincopyimageLayer.borderColor = [UIColor grayColor].CGColor;  //边框颜色  
imageLayer.borderWidth = 2.0;  //边框宽度

运行效果：





设置图片为椭圆角，代码：

view plaincopy to clipboardimageLayer.cornerRadius = 10.0;  //设置layer圆角半径  
imageLayer.masksToBounds = YES;  //隐藏边界  
[html] view plaincopyimageLayer.cornerRadius = 10.0;  //设置layer圆角半径  
imageLayer.masksToBounds = YES;  //隐藏边界

运行效果：





但是由于设置masksToBounds 属性为true所以Layer的阴影效果也就没有了。

之前我都是将图片另外在做有阴影效果的图片，这样显的比较真实，如果阴影部分只是填充边框即可，可以采用两个Layer来实现阴影效果，代码：

view plaincopy to clipboardUIImage *image = [UIImage imageNamed:@"feiche.jpg"];  
//阴影layer  
CALayer *shadowLayer = [CALayer layer];  
shadowLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);  
shadowLayer.backgroundColor = [UIColor blueColor].CGColor;  
shadowLayer.shadowOffset = CGSizeMake(0, 3);  
shadowLayer.cornerRadius = 10.0;  
shadowLayer.shadowRadius = 10.0;  
shadowLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色  
shadowLayer.shadowOpacity = 1.0; //设置阴影的不透明度  
[backLayer addSublayer:shadowLayer];      
  
//添加子image layer  
CALayer *imageLayer = [CALayer layer];  
imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);  
imageLayer.contents = (id) image.CGImage;  
imageLayer.cornerRadius = 10.0;  //设置layer圆角半径  
imageLayer.masksToBounds = YES;  //隐藏边界  
imageLayer.borderColor = [UIColor grayColor].CGColor;  //边框颜色  
imageLayer.borderWidth = 2.0;  
[backLayer addSublayer:imageLayer];  
[html] view plaincopyUIImage *image = [UIImage imageNamed:@"feiche.jpg"];  
//阴影layer  
CALayer *shadowLayer = [CALayer layer];  
shadowLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);  
shadowLayer.backgroundColor = [UIColor blueColor].CGColor;  
shadowLayer.shadowOffset = CGSizeMake(0, 3);  
shadowLayer.cornerRadius = 10.0;  
shadowLayer.shadowRadius = 10.0;  
shadowLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色  
shadowLayer.shadowOpacity = 1.0; //设置阴影的不透明度  
[backLayer addSublayer:shadowLayer];      
  
//添加子image layer  
CALayer *imageLayer = [CALayer layer];  
imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);  
imageLayer.contents = (id) image.CGImage;  
imageLayer.cornerRadius = 10.0;  //设置layer圆角半径  
imageLayer.masksToBounds = YES;  //隐藏边界  
imageLayer.borderColor = [UIColor grayColor].CGColor;  //边框颜色  
imageLayer.borderWidth = 2.0;  
[backLayer addSublayer:imageLayer];

运行后效果：





------转自http://blog.csdn.net/linzhiji/article/details/6748207