斯坦福大学iOS应用开发教程学习笔记(第五课)Protocols,手势识别
主要4部分组成：自动旋转、 Protocols、 手势识别、一个自定义UIView的Demo
1、自动旋转
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)orientation
{
return UIInterfaceOrientationIsPortrait(orientation); // only support portrait
return YES; // support all orientations
return (orientation != UIInterfaceOrientationPortraitUpsideDown); // anything but
}
//包括竖直、上下颠倒、左横向、右横向
当旋转的时候，view的bounds会改变，子view的frame, 子view的子view也会改变。
改变的规则是：struts和springs。
当view的bound改变时，drawRect不会默认调用
就是struts，中间的红色箭头就是springs。
右边红白色的显示屏似的就是用动画告诉你view如何改变。
白色的是父view，红色的是你选中的view。
这个控制在iPhone上一般使用不到，因为屏幕太小了。
幸运的是，有UIView有这么个属性来控制
三种控制方式：
1、
@property (nonatomic) UIViewContentMode contentMode;
UIViewContentMode{Left,Right,Top,Right,BottomLeft,BottomRight,TopLeft,TopRight}
//把你的view的像素点移动到指定位置上
2、缩放的控制属性：
UIViewContentModeScale{ToFill,AspectFill,AspectFit} // bit stretching/shrinking
分别是填充，内容填充，内容适应。 toFill是默认的模式，它会自动缩放像素点填满新的空间，可能会造成图形扭曲。
UIViewContentModeRedraw//重绘
3、
@property (nonatomic) CGRect contentStretch;
指定某一个区域拉伸
初始化一个UIView.
初始化一个UIView
Typical Code
-(void) setip{...}
-(void) awakeFormNib{ [self setup];}
-(id) initWithFrame:(CGRect)aRect{
self=[super initWithFrame:arect];
[self setup];
return self;
}
2、协议procotol
@protocol Foo <Other, NSObject> // implementors must implement Other and NSObject too
- (void)doSomething; // implementors must implement this (methods are @required by default)
@optional
- (int)getSomething; // implementors do not have to implement this
- (void)doSomethingOptionalWithArgument:(NSString *)argument; // also optional
@required
- (NSArray *)getManySomethings:(int)howMany; // back to being “must implement”
@property (nonatomic, strong) NSString *fooProp; // note that you must specify strength
@end
协议没有对应@implementation，就是一个方法和@property的集合
可以定义在自己的头文件里，也可以定义在其他类的头文件中。
实现协议，并使用的语法：
#import “Foo.h” // importing the header file that declares the Foo @protocol
@interface MyClass : NSObject <Foo> // MyClass is saying it implements the Foo @protocol
...
@end
1 必须实现所有的非可选的方法
2 可以声明变量
id <Foo> obj = [[MyClass alloc] init];//编译器喜欢这样的
id <Foo> obj = [NSArray array];//报错
3 可以把它们当参数传递
@property (nonatomic, weak) id <Foo> myFooProperty; // properties too!
协议的主要作用：
实现委托和数据源。//delegate datasource
委托几乎都是weak的，因为被设置为委托的对象通常都是委托对象的所有者或创建者。
比如controller通常把自己设置成view的委托或数据源，你不要它们相互的strong指针指向。
view只会weak指向回controller，反正view也干不了什么，如果controller不在了，view也没什么用了
scrollView例子
@protocol UIScrollViewDelegate
@optional
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)sender;
- (void)scrollViewDidEndDragging:(UIScrollView *)sender willDecelerate:(BOOL)decelerate;
@end
@interface UIScrollView : UIView
@property (nonatomic, weak) id <UIScrollViewDelegate> delegate;
@end
@interface MyViewController : UIViewController <UIScrollViewDelegate>
@property (nonatomic, weak) IBOutlet UIScrollView *scrollView;
@end
@implementation MyViewController
- (void)setScrollView:(UIScrollView *)scrollView {
_scrollView = scrollView;
self.scrollView.delegate = self; // compiler won’t complain
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)sender { return ... };
@end
3、手势识别 UIGestureRecognizer
如何获得触摸事件呢？
得到触摸时间的通知
相应预定义好的手势
UIGestureRecognizer类，它是个抽象类，需要实现。
使用手势识别有两步骤:
先创建一个手势，把它附到UIView上，然后当手势被识别时进行处理。
第一步由controller来完成
第二步由UIView自己完成
从controller添加一个手势到UIView：
- (void)setPannableView:(UIView *)pannableView
{
_pannableView = pannableView;
UIPanGestureRecognizer *pangr =
[[UIPanGestureRecognizer alloc] initWithTarget:pannableView action:@selector(pan:)];
[pannableView addGestureRecognizer:pangr];
}
手势会冲突，但系统会处理好潜在的冲突
target 是手势识别之后的处理者，这里就是view本身来处理。
但pan不是发送者，手势识别调用这个准备发送的消息，所以他不是发送者，手势识别才是
UIPangestureRecognizer的三个方法：
- (CGPoint)translationInView:(UIView *)aView;
- (CGPoint)velocityInView:(UIView *)aView;
- (void)setTranslation:(CGPoint)translation inView:(UIView *)aView;
第一个告诉移动的距离，从上个手势点到这个手势点的距离
第二个告诉移动的速度
第三个是重新设置，第一个方法的setter
手势识别的状态机 state
@property (readonly) UIGestureRecognizerState state;
状态从possible ，手势识别的初始状态
如果手势比较短：recognized
如果持续：Began - Changed变化中 ,最后Ended，手指抬起
还有Failed 和 Cancelled状态，取消或其他操作中断时会有这个情况。
pan:是什么样的呢：
- (void)pan:(UIPanGestureRecognizer *)recognizer
{
if ((recognizer.state == UIGestureRecognizerStateChanged) ||
(recognizer.state == UIGestureRecognizerStateEnded)) {
CGPoint translation = [recognizer translationInView:self];
// move something in myself (I’m a UIView) by translation.x and translation.y
// for example, if I were a graph and my origin was set by an @property called origin
self.origin = CGPointMake(self.origin.x+translation.x, self.origin.y+translation.y);
[recognizer setTranslation:CGPointZero inView:self];
}
}
其他实例的手势：
UIPinchGestureRecognizer //缩放
//scale/velocity
UIRotationGestureRecognizer //旋转手势，两个手指按下，然后旋转，是个弧度，不是角度。
//rotation/velocity
UISwipeGestureRecognizer 滑动手势， 一个或多个手指滑动，
//direction/numerOfTouchesRequired
UITapGestureRecognizer //点击手势
//numofTapsRequired/numerOfTouchesRequired
4 演示Demo
整个Demo的下载地址：https://github.com/junxianhu/Happiness
Happiness
通过drawRect画出一个笑脸，在捕捉手势，放大缩小，以及向上，向下拖动，改变笑脸和哭脸
贴几个主要代码：
ViewController.m
//
// ViewController.m
// Happiness
//
// Created by cipher on 15/10/7.
// Copyright (c) 2015年 com.lab1411.cipher. All rights reserved.
//
#import "ViewController.h"
#import "FaceView.h"
//协议放这<FaceViewDataSource> 私有的
@interface ViewController () <FaceViewDataSource>
@property(nonatomic,weak) IBOutlet FaceView *faceView;
@end
@implementation ViewController
@synthesize happiness = _happiness;
@synthesize faceView = _faceView;
-(void)setHappiness:(int)happiness{
_happiness=happiness;
[self.faceView setNeedsDisplay];
}
-(void)setFaceView:(FaceView *)faceView{
_faceView = faceView;
//这里增加的target 一定是UIPinchGestureRecognizer，UIGestureRecognizer无法捕捉
[self.faceView addGestureRecognizer:[[UIPinchGestureRecognizer alloc] initWithTarget:self.faceView action:@selector(pinch:)]];
//控制笑脸
[self.faceView addGestureRecognizer:[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleHappinessGesture:)]];
self.faceView.dataSource = self;
}
-(void)handleHappinessGesture:(UIPanGestureRecognizer *)gesture{
if (gesture.state == UIGestureRecognizerStateChanged || gesture.state == UIGestureRecognizerStateEnded) {
CGPoint translation = [gesture translationInView:self.faceView];
self.happiness -= translation.y / 2;
[gesture setTranslation:CGPointZero inView:self.faceView];
}
}
-(float)smileForFaceView:(FaceView *)sender{
return (self.happiness - 50) / 50.0;
}
-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation{
return YES;
}
@end
FaceView.h
//
// FaceView.h
// Happiness
//
// Created by cipher on 15/10/7.
// Copyright (c) 2015年 com.lab1411.cipher. All rights reserved.
//
#import <UIKit/UIKit.h>
@class FaceView;
@protocol FaceViewDataSource
//这里的FaceView变量未定义，在下面菜才定义，用class解决，前向引用
-(float)smileForFaceView:(FaceView *)sender;
@end
@interface FaceView : UIView
@property (nonatomic) CGFloat scale;
//让该方法成为public
-(void)pinch:(UIPinchGestureRecognizer *)gesture;
//协议
@property (nonatomic,weak) IBOutlet id<FaceViewDataSource> dataSource;
@end
FaceView.m
//
// FaceView.m
// Happiness
//
// Created by cipher on 15/10/7.
// Copyright (c) 2015年 com.lab1411.cipher. All rights reserved.
//
#import "FaceView.h"
#define DEFAULT_SCALE 0.90
#define EYE_H 0.35
#define EYE_Y 0.35
#define EYE_RADIUS 0.10
#define MOUTH_H 0.45
#define MOUTH_Y 0.40
#define MOUTH_SMILE 0.25
@implementation FaceView
@synthesize dataSource=_dataSource;
@synthesize scale=_scale;
-(CGFloat)scale{
if (!_scale) {
return DEFAULT_SCALE;
}else{
return _scale;
}
}
-(void)setScale:(CGFloat)scale{
if (scale != _scale) {
_scale=scale;
[self setNeedsDisplay];
}
}
-(void)pinch:(UIPinchGestureRecognizer *)gesture{
NSLog(@"dfsdf");
if (gesture.state == UIGestureRecognizerStateChanged || gesture.state == UIGestureRecognizerStateEnded) {
self.scale *= gesture.scale;
gesture.scale = 1;
}
}
-(void) setup{
self.contentMode = UIViewContentModeRedraw;
}
-(void)awakeFromNib{
[self setup];
}
-(id)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self) {
[self setup];
}
return self;
}
-(void)drawCircleAtPoint:(CGPoint)p withRadius:(CGFloat)radius inContext:(CGContextRef)context{
UIGraphicsPushContext(context);
CGContextBeginPath(context);
CGContextAddArc(context,p.x,p.y, radius, 0, 2*M_PI, YES);
CGContextStrokePath(context);
UIGraphicsPopContext();
}
-(void) drawRect:(CGRect)rect{
CGContextRef context = UIGraphicsGetCurrentContext();
//draw face circle
CGPoint midPoint;
midPoint.x = self.bounds.origin.x + self.bounds.size.width/2;
midPoint.y = self.bounds.origin.y + self.bounds.size.height/2;
CGFloat size =self.bounds.size.width/2;
if (self.bounds.size.height < self.bounds.size.width) {
size = self.bounds.size.height/2;
}
// size *= DEFAULT_SCALE;
NSLog(@"%f",self.scale);
size *= self.scale;
CGContextSetLineWidth(context, 5.0);
[[UIColor blueColor] setStroke];
[self drawCircleAtPoint:midPoint withRadius:size inContext:context];
//draw eyes
CGPoint eyePoint;
eyePoint.x = midPoint.x - size * EYE_H;
eyePoint.y = midPoint.y - size * EYE_Y;
[self drawCircleAtPoint:eyePoint withRadius:size*EYE_RADIUS inContext:context];
eyePoint.x += size * EYE_H * 2;
[self drawCircleAtPoint:eyePoint withRadius:size*EYE_RADIUS inContext:context ];
//no nose
//draw mouth
CGPoint mouthStart;
mouthStart.x = midPoint.x - MOUTH_H * size;
mouthStart.y = midPoint.y + MOUTH_Y * size;
CGPoint mouthEnd = mouthStart;
mouthEnd.x += MOUTH_H * size * 2;
CGPoint mouthCP1 = mouthStart;
mouthCP1.x += MOUTH_H * size * 2/3;
CGPoint mouthCP2 = mouthEnd;
mouthCP2.x -= MOUTH_H * size * 2/3;
// float smile = 1;//this shoule be dlegated it's our view's data
float smile = [self.dataSource smileForFaceView:self];
if (smile < -1) {
smile = -1;
}
if (smile > 1) {
smile = 1;
}
CGFloat smileOffset = MOUTH_SMILE * size * smile;
mouthCP1.y += smileOffset;
mouthCP2.y += smileOffset;
CGContextBeginPath(context);
CGContextMoveToPoint(context, mouthStart.x, mouthStart.y);
CGContextAddCurveToPoint(context, mouthCP1.x, mouthCP1.y, mouthCP2.x, mouthCP2.y, mouthEnd.x, mouthEnd.y);
CGContextStrokePath(context);
}
@end
