手势在用户交互中有着举足轻重的作用,这篇文字简单的介绍了iOS中的手势,并通过手势对控件进行变形处理。

手势

iOS手势分为下面这几种:

  • UITapGestureRecognizer(点按)
  • UIPanGestureRecognizer(拖动)
  • UIScreenEdgePanGestureRecognizer (边缘拖动)
  • UIPinchGestureRecognizer(捏合)
  • UIRotationGestureRecognizer(旋转)
  • UILongPressGestureRecognizer(长按)
  • ​UISwipeGestureRecognizer(轻扫)

这些手势大都继承于UIGestureRecognizer类,(UIScreenEdgePanGestureRecognizer继承于UIPanGestureRecognizer类),

需要说明的是这些手势只有一个是离散型手势,那就是UITapGestureRecognizer,一旦识别就无法取消,而且只会调用一次手势操作事件。

换句话说其他手势是连续型手势,而连续型手势的特点就是:会多次调用手势操作事件,而且在连续手势识别后可以取消手势。

从下图可以看出两者调用操作事件的次数是不同的:

这些手势类有着以下共同的方法:

创建方法:

- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action;

移除方法:

- (void)removeTarget:(nullable id)target action:(nullable SEL)action;

添加事件:

- (void)addTarget:(id)target action:(SEL)action;

还有下面这些属性等:

@property(nonatomic,readonly) UIGestureRecognizerState state;// 手势状态

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
     UIGestureRecognizerStatePossible,   // 尚未识别是何种手势操作(但可能已经触发了触摸事件),默认状态
     UIGestureRecognizerStateBegan,      // 手势已经开始,此时已经被识别,但是这个过程中可能发生变化,手势操作尚未完成
     UIGestureRecognizerStateChanged,    // 手势状态发生转变
     UIGestureRecognizerStateEnded,      // 手势识别操作完成(此时已经松开手指)
     UIGestureRecognizerStateCancelled,  // 手势被取消,恢复到默认状态
     UIGestureRecognizerStateFailed,     // 手势识别失败,恢复到默认状态
     UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // 手势识别完成,同UIGestureRecognizerStateEnded
 };

@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate; // 代理

@property(nonatomic, getter=isEnabled) BOOL enabled; 

当然我们也可以自定义手势来实现特殊的需求,关于自定义手势可以看这篇博客.

接下来我们来看看这些常用手势的用法.

UITapGestureRecognizer(点按)

Tap手势有两个属性,

  • numberOfTapsRequired
  • numberOfTouchesRequired:

numberOfTapsRequired为触发事件需要点击的次数,默认是1;

numberOfTouchesRequired为触发事件需要的几个手指点按,默认是1;

若都设置为2,就需要两个手指同时点按2次才会触发事件。

Tap手势也是我们最常用的手势之一, 比如点击ImageView跳转到其他界面,或者双击图片放大缩小等。

创建:

	UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tap:)];
    tap.numberOfTapsRequired = 2;
    tap.numberOfTouchesRequired = 1;
    [self.imageView addGestureRecognizer:tap];

UIPanGestureRecognizer(拖动)

Pan手势的属性和方法:

  • @property (nonatomic) NSUInteger minimumNumberOfTouches __TVOS_PROHIBITED;
  • @property (nonatomic) NSUInteger minimumNumberOfTouches __TVOS_PROHIBITED;
  • -(CGPoint)translationInView:(nullable UIView *)view;
  • -(void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;
  • -(CGPoint)velocityInView:(nullable UIView *)view;

translationInView:方法获取View的偏移量;

setTranslation:方法设置手势的偏移量;

velocityInView:方法获取速度;

所以手势的创建方法都类似,这里就不在一一列举了。

UIScreenEdgePanGestureRecognizer (边缘拖动)

ScreenEdgePan继承于UIPanGestureRecognizer,在屏幕边缘滑动才会触发

  • @property (readwrite, nonatomic, assign) UIRectEdge edges;

edges为指定边缘拖动触发的边,是一个枚举:

typedef NS_OPTIONS(NSUInteger, UIRectEdge) {
    UIRectEdgeNone   = 0,
    UIRectEdgeTop    = 1 << 0,
    UIRectEdgeLeft   = 1 << 1,
    UIRectEdgeBottom = 1 << 2,
    UIRectEdgeRight  = 1 << 3,
    UIRectEdgeAll    = UIRectEdgeTop | UIRectEdgeLeft | UIRectEdgeBottom | UIRectEdgeRight
} NS_ENUM_AVAILABLE_IOS(7_0);

其他方法和Tap手势一致,主要用于像左右抽屉视图的变换等处理。

UIPinchGestureRecognizer(捏合)

Pinch手势有两个属性:

  • @property (nonatomic) CGFloat scale;
  • @property (nonatomic,readonly) CGFloat velocity;

scale:捏合比例

velocity:捏合速度 = scale/second

UIRotationGestureRecognizer(旋转)

Rotation手势和Pinch手势类似,同样有两个手势:

  • @property (nonatomic) CGFloat rotation;
  • @property (nonatomic,readonly) CGFloat velocity;

rotation:旋转弧度,注意,这里的单位是弧度

velocity:旋转速度

UILongPressGestureRecognizer(长按)

LongPress的属性:

  • @property (nonatomic) NSUInteger numberOfTapsRequired; // Default is 0.
  • @property (nonatomic) NSUInteger numberOfTouchesRequired __TVOS_PROHIBITED; // Default is 1.
  • @property (nonatomic) CFTimeInterval minimumPressDuration;
  • @property (nonatomic) CGFloat allowableMovement;

numberOfTapsRequirednumberOfTouchesRequired和Tap手势类似,都是指定触发需要的点击次数和手指数量,但是LongPress手势的numberOfTapsRequired是指定长按前需要点击的次数。

minimumPressDuration:触发时间

allowableMovement:允许长按时间触发前允许手指滑动的范围。若是你在长按时手指移动,该长按手势将会失败,allowableMovement设置你能容忍的滑动范围,默认是10.

变形


iOS的变形指的是图片的旋转、平移和缩放。这些变形可以和上面介绍的手势结合,完成许多变形操作。

说变形前我们来看看CGAffineTransformCGAffineTransform为一个结构体:

struct CGAffineTransform {
    CGFloat a, b, c, d;
    CGFloat tx, ty;
};

我们输出一个控件的transform看看

NSLog(@"%@", NSStringFromCGAffineTransform(self.label.transform));

输出

2016-12-22 17:01:19.211 手势[6489:1481987] [1, 0, 0, 1, 0, 0]

我们可以看到输出了一个长度为6的数组:[1, 0, 0, 1, 0, 0],并且我们可以猜测对应结构体中的[a, b, c, d, tx, ty],并且默认的transform值就是[1, 0, 0, 1, 0, 0]

想进一步了解可以看这篇《iOS CGAffineTransform详解》

对iOS控件进行变形实际就是对控件transform属性进行操作。

但是我们使用中,使用已经封装好的的API对控件进行变形处理。分别是:

  • CGAffineTransformScale()
  • CGAffineTransformTranslate()
  • CGAffineTransformRotate()

和:

  • CGAffineTransformMakeScale()
  • CGAffineTransformMakeTranslate()
  • CGAffineTransformMakeRotate()

这些API都是对设置CGAffineTransform的一个封装,针对[a, b, c, d, tx, ty]中不同的位置进行操作。

下面我们在ViewController创建一个UILabel控件。然后对它进行变形操作。

缩放

首先来看一个缩放操作

// 缩放到90%(相对)
self.label.transform = CGAffineTransformScale(self.label.transform, 0.9, 0.9);
    
NSLog(@"%@", NSStringFromCGAffineTransform( self.label.transform));

输出:

2016-12-22 17:26:25.074 手势[6526:1564064] [0.90000000000000002, 0, 0, 0.90000000000000002, 0, 0]
2016-12-22 17:26:26.096 手势[6526:1564064] [0.81000000000000005, 0, 0, 0.81000000000000005, 0, 0]
2016-12-22 17:26:26.963 手势[6526:1564064] [0.72900000000000009, 0, 0, 0.72900000000000009, 0, 0]
2016-12-22 17:26:28.830 手势[6526:1564064] [0.65610000000000013, 0, 0, 0.65610000000000013, 0, 0]

我们再看看另一个缩放:

self.label.transform = CGAffineTransformMakeScale(0.9, 0.9);

NSLog(@"%@", NSStringFromCGAffineTransform( self.label.transform));

输出

2016-12-22 17:32:32.972 手势[6581:1600236] [0.90000000000000002, 0, 0, 0.90000000000000002, 0, 0]
2016-12-22 17:32:34.164 手势[6581:1600236] [0.90000000000000002, 0, 0, 0.90000000000000002, 0, 0]
2016-12-22 17:32:35.246 手势[6581:1600236] [0.90000000000000002, 0, 0, 0.90000000000000002, 0, 0]

对比可以发现CGAffineTransformScale()CGAffineTransformMakeScale()的区别在于,CGAffineTransformScale()实在原理的基础上在进行缩放操作,而CGAffineTransformMakeScale()直接将缩放值设定为0.9不变了。

缩放操作变动的是构体中[a, b, c, d, tx, ty]ad,值和变形系数Scale是相对应的,大于1是放大,小于1是缩小。。

a是横向缩放, d是纵向缩放。

平移

先来看一个平移操作:

self.label.transform = CGAffineTransformTranslate(self.label.transform, 10, 10);
    NSLog(@"%@", NSStringFromCGAffineTransform( self.label.transform));

输出

2016-12-22 17:40:38.568 手势[6608:1631232] [1, 0, 0, 1, 10, 10]
2016-12-22 17:40:40.833 手势[6608:1631232] [1, 0, 0, 1, 20, 20]
2016-12-22 17:40:41.834 手势[6608:1631232] [1, 0, 0, 1, 30, 30]
2016-12-22 17:40:42.532 手势[6608:1631232] [1, 0, 0, 1, 40, 40]
2016-12-22 17:40:43.162 手势[6608:1631232] [1, 0, 0, 1, 50, 50]

我们可以看到label往右下角移动

对应xy的正向坐标为右下角。

旋转

self.label.transform = CGAffineTransformRotate(self.label.transform, M_PI_2);
NSLog(@"%@", NSStringFromCGAffineTransform( self.label.transform));

输出:

2016-12-22 17:59:43.680 手势[6667:1717130] [6.123233995736766e-17, 1, -1, 6.123233995736766e-17, 0, 0]

可以看到label顺时针旋转了π/2弧度(90°)。

手势结合变形


手势结合变形就是通过手势对控件变形处理。

上代码:

#import "ViewController.h"

@interface ViewController ()<UIGestureRecognizerDelegate>
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
//    CGAffineTransform *mytransform = self.imageView.transform;
    self.imageView.userInteractionEnabled = YES;
    //1双击 恢复
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tap:)];
    tap.numberOfTapsRequired = 2;
    tap.numberOfTouchesRequired = 1;
    [self.imageView addGestureRecognizer:tap];
    
    //2拖拽
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
//    pan.delegate = self;
    [self.imageView addGestureRecognizer:pan];
    
    //3捏合
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinch:)];
    pinch.delegate = self;
    [self.imageView addGestureRecognizer:pinch];
    
    //4旋转
    UIRotationGestureRecognizer *rotaion = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotaion:)];
//    pinch.delegate = self;
    [self.imageView addGestureRecognizer:rotaion];
    
    // 长按
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
    longPress.numberOfTapsRequired = 0;
    longPress.minimumPressDuration = 1;
//    longPress.allowableMovement = 3;
    [self.imageView addGestureRecognizer:longPress];
    
}
- (void)tap:(UITapGestureRecognizer *)sender{
    
    NSLog(@"tap!");
    
    //恢复
    self.imageView.transform = CGAffineTransformIdentity;
    
}
- (void)pan:(UIPanGestureRecognizer *)sender{
//    CGPoint center = self.imageView.center;
//    if (center.x < 0){
//        center.x = 0;
//    }else{
//        center.x += [sender translationInView:self.view].x;
//    }
//    
//    center.y += [sender translationInView:self.view].y;
//    self.imageView.center = center;
    //将相对偏移量清零
//    [sender setTranslation:CGPointMake(0, 0) inView:self.view];
    
    self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, [sender translationInView:self.imageView].x, [sender translationInView:self.imageView].y);
    [sender setTranslation:CGPointZero inView:self.view];
    
}

- (void)pinch:(UIPinchGestureRecognizer *)sender{
    
    CGFloat  scale = sender.scale;
    self.imageView.transform = CGAffineTransformScale(self.imageView.transform, scale, scale);
    [sender setScale:1];
   
}

- (void)rotaion:(UIRotationGestureRecognizer *)sender{
    //获取旋转弧度
    CGFloat rotation = sender.rotation;
    self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, rotation);
    sender.rotation = 0;
    
//    self.imageView.transform = CGAffineTransformMakeRotation(sender.rotation);
    
}

- (void)longPress:(UILongPressGestureRecognizer *)sender {
    
    NSLog(@"longPress:%@", sender);
    
    // 判断长按事件触发
    if (sender.state == UIGestureRecognizerStateBegan) {
        self.imageView.transform = CGAffineTransformMake(1, 0, 0, 1, 0, 0);
    }
    
}


//希望两个手势共存
//遵守 UIGestureRecognizerDelegate 协议
//实现方法 -(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
//将要同时实现的手势设置代理 pinch.delegate = self; pinch.delegate = self;

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
    return YES;
}

有几点需要注意:

  • 给本身没有交互功能的控件()imagView, UIlabel, View等)添加手势,要设置userInteractionEnabledYES,否则识别不了手势
  • 想要手势共存需要:
    • 遵守 UIGestureRecognizerDelegate 协议
    • 实现-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer方法,返回YES
    • 将要同时实现的手势设置代理 pinch.delegate = self; pinch.delegate = self

在storyboard中添加手势

storyboard的控件栏中我们可以看到这些手势控件:

storyboard中的手势控件

使用方法:

  1. 直接将手势控件拖到要添加的视图上

  2. 关联手势事件

  3. 设置手势属性

注意:若想同时识别多个手势,方法和上面相同,遵循协议,实现方法,设置代理,不过代理可以手动关联。