随意细解：UI -- 设计模式、手势识别

target/Action设计模式

举例：点击view实现点击功能，改变背景颜色（类似button的addtarget方法）

创建ButtonView，遵守协议：

在ButtonView.h中：为了方便调用，声明成属性

@property (nonatomic, retain) id target;
@property (nonatomic, assign) SEL action;
// 初始化方法
- (instancetype)initWithFrame:(CGRect)frame target:(id)target action:(SEL)action;

在ButtonView.m中：

- (void)dealloc
{
[self.target release];
[super dealloc];
}

- (instancetype)initWithFrame:(CGRect)frame target:(id)target action:(SEL)action
{
self = [super initWithFrame:frame];
if (self) {
// 初始化时，对属性进行赋值
self.target = target;
self.action = action;

}
return self;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
// 使用self.target对象调用 action方法
// 让一个对象 去调用这个对象类里的方法
// Object 可携带的参数
[self.target performSelector:self.action withObject:self];
}

创建RootViewController作为根控制器

- (void)viewDidLoad {
[super viewDidLoad];
ButtonView *buttonView = [[ButtonView alloc]initWithFrame:CGRectMake(100, 100, 100, 100) target:self action:@selector(buttonClick:)];
buttonView.backgroundColor = [UIColor redColor];
[self.view addSubview:buttonView];
[buttonView release];
}
- (void)buttonClick:(ButtonView *)buttonView
{
buttonView.backgroundColor = [UIColor blackColor];
NSLog(@"触发了");
}

delegate代理模式

不管是target/Action设计模式，代理设计模式还是 MVC设计模式，中心只有一个，解耦，提高代码的复用性。

举例说明：点击ImageView，实现点击事件，改变背景颜色，并且遵循MVC设计模式

创建 ButtonImageView，并创建协议

在@interface之前声明协议，因为需要类本身作为参数，所以使用@class方法告诉文件，ButtonImageView是一个类：(ButtonImageView.h文件中)

@class ButtonImageView;
@protocol  ButtonImageViewDElegate <NSObject>

- (void)ButtonImageViewClick:(ButtonImageView *)imageView;

@end

设置代理

需要调用ButtonImageView的代理方法，所以将delegate设置为属性：（ButtonImageView.h文件中）

@property (nonatomic, assign) id<ButtonImageViewDElegate> delegate;

代理属性为什么要声明成assign?

防止循环引用从而造成的内存泄露。解释：

假如 A是B的代理，B也是A的代理，如果是 retain
[[A alloc]init];      A:1
[[B alloc]init];      B:1
A.delegate = B;       B:2
B.delegate = A;       A:2
[A release];          A:1
[B release];          B:1
A和B的引用计数都是1，无法释放，造成内存泄露。

实现 touchesEnded 方法：（ButtonImageView.m文件中）

注：声明delegate属性，需要重写dealloc方法

- (void)dealloc
{
[self.delegate release];
[super dealloc];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
// 判断保护，判断delegateshif响应点击方法
if ([_delegate respondsToSelector:@selector(ButtonImageViewClick:)]) {
// 调用代理方法
[_delegate ButtonImageViewClick:self];
}
}

创建MyView ， 调用ButtonImageView

为了外部可以直接调用imageView，将imageView声明称属性：（在MyView.h中）

// 引入头文件
#import "ButtonImageView.h"

// 声明属性
@property (nonatomic, retain) ButtonImageView *imageView;

在MyView中重写initWithFrame方法

- (void)dealloc
{
[self.imageView release];
[super dealloc];
}

- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.imageView = [[ButtonImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
[self addSubview:self.imageView];
[self.imageView release];
}
return self;
}

创建 RootViewController ，作为根控制器。遵循协议（在RootViewController.h文件中）

// 引入头文件
#import "ButtonImageView.h"
@interface RootViewController : UIViewController <ButtonImageViewDElegate>

实现协议中的方法

- (void)viewDidLoad {
[super viewDidLoad];
MyView *myView = [[MyView alloc]initWithFrame:[UIScreen mainScreen].bounds];
// 设置代理
myView.imageView.delegate = self;
self.view = myView;
[myView release];
}
// 实现协议中的方法
- (void)ButtonImageViewClick:(ButtonImageView *)imageView
{
imageView.backgroundColor = [UIColor yellowColor];
}

手势识别

手势类 UIGestureRecognizer，这个类是个抽象类，其具体功能交给子类去实现。

创建ImageView，添加手势：

UIImageView *imageView = [[UIImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
[self.view addSubview:imageView];
imageView.image = [UIImage imageNamed:@"C8"];
// 打开交互
imageView.userInteractionEnabled = YES;
[imageView release];

轻拍

viewDidLoad方法中：

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapAction:)];
// 添加手势到视图上
[imageView addGestureRecognizer:tap];
[tap release];

实现轻拍方法

- (void)tapAction:(UITapGestureRecognizer *)tap
{
UIImageView *imageView = (UIImageView *)tap.view;
imageView.image = [UIImage imageNamed:@"C1"];
NSLog(@"你拍我了");
}

长按

viewDidLoad方法中：

UILongPressGestureRecognizer *longPress= [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPressAction:)];
// 设置长按时间
longPress.minimumPressDuration = 2.0;
// 添加到视图上
[imageView addGestureRecognizer:longPress];
[longPress release];

实现长按方法

- (void)longPressAction:(UILongPressGestureRecognizer *)longPress
{
// 判断一下手势状态，长按，只需要触发一次
if (longPress.state == UIGestureRecognizerStateBegan) {
NSLog(@"长按触发了多少次？");
UIImageView *imageView = (UIImageView *)longPress.view;
imageView.image = [UIImage imageNamed:@"image.jpg"];
NSLog(@"你按我了");
}
}

旋转

viewDidLoad方法中：

UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotationAction:)];

[imageView addGestureRecognizer:rotation];
[rotation release];

实现旋转方法

- (void)rotationAction:(UIRotationGestureRecognizer *)rotation
{
// 形变属性 transform
// 参数1：改变形变属性的视图
// 参数2：根据弧度去创建
rotation.view.transform = CGAffineTransformRotate(rotation.view.transform, rotation.rotation);
// 每次转需要把旋转的角度重置为0
// 因为要接替上一次的角度 开始旋转
rotation.rotation = 0;
NSLog(@"旋转了");
}

捏合

viewDidLoad方法中：

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinchAction:)];
[imageView addGestureRecognizer:pinch];
[pinch release];

实现捏合方法

- (void)pinchAction:(UIPinchGestureRecognizer *)pinch
{
// 根据缩放的刻度（比例）改变形变属性
// 根据捏合的比较，去改变形变属性
pinch.view.transform = CGAffineTransformScale(pinch.view.transform, pinch.scale , pinch.scale);
// 重置捏合的比例
pinch.scale = 1;
NSLog(@"捏合");
}

平移

viewDidLoad方法中：

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panAction:)];
[imageView addGestureRecognizer:pan];
[pan release];

实现平移方法

- (void)panAction:(UIPanGestureRecognizer *)pan
{
// 获取平移的点(相对于要平移的视图)
CGPoint p = [pan translationInView:pan.view];
// 根据这个点改变形变属性
pan.view.transform = CGAffineTransformTranslate(pan.view.transform, p.x, p.y);
// 重置这个点
[pan setTranslation:CGPointMake(0, 0) inView:pan.view];
NSLog(@"平移");
}

轻扫

viewDidLoad方法中：

UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeAction:)];
// 设置左右扫的方向
swipe.direction = UISwipeGestureRecognizerDirectionLeft;

[imageView addGestureRecognizer:swipe];
[swipe release];

实现轻扫方法

- (void)swipeAction:(UISwipeGestureRecognizer *)swipe
{

NSLog(@"左扫");
}

边缘扫

viewDidLoad方法中：

UIScreenEdgePanGestureRecognizer *screenEdgePan = [[UIScreenEdgePanGestureRecognizer alloc]initWithTarget:self action:@selector(screenEdgePanAction:)];
// 设置从哪个边缘开始扫
screenEdgePan.edges = UIRectEdgeRight;
[imageView addGestureRecognizer:screenEdgePan];
[screenEdgePan release];

实现边缘扫方法

- (void)screenEdgePanAction:(UIScreenEdgePanGestureRecognizer *)screenEdgePan
{
NSLog(@"边缘扫一定要靠近屏幕边缘开始扫");
}