锚点
了解游戏的人一般都知道锚点，在UIView中我们很少用到。anchorPoint位于图层的中点，所以图层的将会以这个点为中心放置。anchorPoint属性并没有被UIView接口暴露出来，这也是视图的position属性被叫做“center”的原因。但是图层的anchorPoint可以被移动，比如你可以把它置于图层frame的左上角，于是图层的内容将会向右下角的position方向移动（图3.3），而不是居中了。
Demo:
主要是看下指针的位置
Xib指针位置如图（锚点在中心位置）：
最后效果如下:
Demo代码：
代码语言：javascript复制//
// ClockViewController.m
// LayerStudyDemo
//
// Created by apple on 2017/9/25.
// Copyright © 2017年 ZY. All rights reserved.
//
#import "ClockViewController.h"
@interface ClockViewController ()
@property (weak, nonatomic) IBOutlet UILabel *hourLabel;
@property (weak, nonatomic) IBOutlet UILabel *minuteLabel;
@property (weak, nonatomic) IBOutlet UILabel *secondLabel;
@property (nonatomic, weak) NSTimer *timer;
@end
@implementation ClockViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(showTime) userInfo:nil repeats:YES];
}
-(void)showTime{
NSCalendar * calendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierChinese];
NSUInteger units = NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *components = [calendar components:units fromDate:[NSDate date]];
CGFloat hoursAngle = (components.hour / 12.0) * M_PI * 2.0;
//calculate hour hand angle //calculate minute hand angle
CGFloat minsAngle = (components.minute / 60.0) * M_PI * 2.0;
//calculate second hand angle
CGFloat secsAngle = (components.second / 60.0) * M_PI * 2.0;
//设置锚点
self.hourLabel.layer.anchorPoint =self.minuteLabel.layer.anchorPoint =self.secondLabel.layer.anchorPoint = CGPointMake(0.5f, 0.9f);
//rotate hands
self.hourLabel.transform = CGAffineTransformMakeRotation(hoursAngle);
self.minuteLabel.transform = CGAffineTransformMakeRotation(minsAngle);
self.secondLabel.transform = CGAffineTransformMakeRotation(secsAngle);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
@end坐标系和Hit Testing
CALayer并不关心任何响应链事件，所以不能直接处理触摸事件或者手势。但是它有一系列的方法帮你处理事件：-containsPoint:和-hitTest:。
-containsPoint:接受一个在本图层坐标系下的CGPoint，如果这个点在图层frame范围内就返回YES。
-hitTest:方法同样接受一个CGPoint类型参数，而不是BOOL类型，它返回图层本身，或者包含这个坐标点的叶子节点图层。这意味着不再需要像使用-containsPoint:那样，人工地在每个子图层变换或者测试点击的坐标。如果这个点在最外面图层的范围之外，则返回nil。
//
// HitTestingViewController.m
// LayerStudyDemo
//
// Created by apple on 2017/9/25.
// Copyright © 2017年 ZY. All rights reserved.
//
#import "HitTestingViewController.h"
@interface HitTestingViewController ()
@property (weak, nonatomic) IBOutlet UIView *wildView;
@property (nonatomic, strong) CALayer *innerLayer;
@end
@implementation HitTestingViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self creatInnerLayer];
}
-(void)creatInnerLayer{
self.innerLayer = [CALayer layer];
self.innerLayer.frame = CGRectMake((self.wildView.frame.size.width-100)/2, (self.wildView.frame.size.height-100)/2, 100.0f, 100.0f);
self.innerLayer.backgroundColor = [UIColor blueColor].CGColor;
//add it to our view
[self.wildView.layer addSublayer:self.innerLayer];
}
// containsPoint 判断较麻烦，需要把坐标转换图层成每个坐标系下的坐标
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
CGPoint point = [[touches anyObject] locationInView:self.view];
//将点击的点从以 self.view.layer 为父类的坐标系转到self.wildView.layer为父类的坐标系
point = [self.wildView.layer convertPoint:point fromLayer:self.view.layer];
if ([self.wildView.layer containsPoint:point]) {
//convert point to blueLayer’s coordinates
point = [self.innerLayer convertPoint:point fromLayer:self.wildView.layer];
if ([self.innerLayer containsPoint:point]) {
[[[UIAlertView alloc] initWithTitle:@"Inside innerLayer Layer"
message:nil
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil] show];
} else {
[[[UIAlertView alloc] initWithTitle:@"Inside wildView Layer"
message:nil
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil] show];
}
}
}
//-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
//
// CGPoint point = [[touches anyObject] locationInView:self.view];
// //返回点击layer
// CALayer * hitLayer = [self.wildView.layer hitTest:point];
// if (hitLayer==self.innerLayer) {
//
// [[[UIAlertView alloc] initWithTitle:@"Inside innerLayer Layer"
// message:nil
// delegate:nil
// cancelButtonTitle:@"OK"
// otherButtonTitles:nil] show];
// } else if(hitLayer==self.wildView.layer){
// [[[UIAlertView alloc] initWithTitle:@"Inside wildView Layer"
// message:nil
// delegate:nil
// cancelButtonTitle:@"OK"
// otherButtonTitles:nil] show];
// }else{
// [[[UIAlertView alloc] initWithTitle:@"Inside View"
// message:nil
// delegate:nil
// cancelButtonTitle:@"OK"
// otherButtonTitles:nil] show];
// }
//}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@endDEMO地址
