<极客学院>视频教程学习笔记－iOS中CALayer的使用

<1>CALayer简介

1、CALayer一般作为UIView的容器而使用。

2、CALayer是一个管理者图片载体（image－based content）的层结构

3、直接修改单独创建出的CALayer的属性可以触发隐式动画

4、UIView中的CALayer动画必须显式触发才能生效

 开篇代码练习：

#import "ViewController.h"

@interface ViewController ()
//2单独创建一个layer
@property (nonatomic,strong) CALayer *layer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //1创建一个容器View
    UIView *containerview = [[UIView alloc] initWithFrame:CGRectMake(50, 200, 100, 3)];
    containerview.backgroundColor = [UIColor blueColor];
    [self.view addSubview:containerview];
    //3使用并设置layer的相关值
    self.layer = [CALayer layer];
    [self.layer setFrame:CGRectMake(0, 0, 50, 3)];
    self.layer.backgroundColor = [UIColor redColor].CGColor;//别忘了最后面还要一个  .CGColor
    [containerview.layer addSublayer:self.layer];
}


@end

 继续努力敲代码：

#import "ViewController.h"

@interface ViewController ()
//创建一个独立的layer
@property (nonatomic,strong) CALayer *layer;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //创建一个UIView作为父容器
    UIView *containerView = [[UIView alloc] initWithFrame:CGRectMake(100, 200, 200, 3)];
    containerView.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:containerView];
    //layer
    self.layer = [CALayer layer];
    self.layer.frame = CGRectMake(0, 0, 10, 3);
    self.layer.backgroundColor = [UIColor blueColor].CGColor;
    [containerView.layer addSublayer:self.layer];
    
    // 使用了消息处理方法，并添加layerAnimatiion方法
    [self performSelector:@selector(layerAnimation) withObject:nil afterDelay:3.f];
    
}
-(void)layerAnimation{
    NSLog(@"修改了layer");
    self.layer.frame = CGRectMake(0, 0, 150, 3);
}
@end