触摸与手势

触摸（UITouch）

简介

• UIView继承于UIResponder是一种响应者类，可以响应用户触摸事件。

• UIViewController也是继承于UIResponder，属于响应者类。

• UIKit 继承链：

• UIResponder响应者类提供了便利的方法来处理触摸事件：

  • 触摸开始
  • 触摸移动
  • 触摸结束
  • 触摸取消

• UITouch方法：

// 触摸开始
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; // 触摸移动 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; // 触摸结束 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; // 触摸取消 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;

场景举例

有时需要用户触摸某个视图移动，并且视图会跟着触摸手势轨迹的移动的时候，我们可通过触摸移动方法touchesMoved实现。

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSLog(@"%@", NSStringFromSelector(_cmd));

    UITouch *touch = [touches anyObject];

    if (touch.view == _showView) {
        // 前一个点
        CGPoint previousLocation = [touch previousLocationInView:_showView];
        // 当前点
        CGPoint currentLocation = [touch locationInView:_showView];
        // 偏移
        CGPoint offset = CGPointMake(currentLocation.x - previousLocation.x,currentLocation.y - previousLocation.y);
        // 改变视图位置
        _showView.center = CGPointMake(_showView.center.x + offset.x,_showView.center.y + offset.y);
    }
}

手势（UIGestureRecognizer）

简介

• Cocoa Touch中为我们提供了便利的手势处理类：UIGestureRecognizer

• 由UIGestureRecognizer衍生的常用子类有：

  • 点击手势：UITapGestureRecognizer

  • 缩放手势：UIPinchGestureRecognizer

  • 旋转手势：UIRotationGestureRecognizer

  • 滑动手势：UISwipeGestureRecognizer

  • 拖动手势：UIPanGestureRecognizer

  • 长按手势：UILongPressGestureRecognizer

• 初始化手势：

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

• 添加或移除指定视图上的手势：

// 添加手势
- (void)addGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer; // 移除手势 - (void)removeGestureRecognizer:(UIGestureRecognizer*)gestureRecognizer;

• 当同一视图上存在多个手势时，会出现冲突，可以使用一个方法来避免多手势带来的冲突：

- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;

代码示例

#import "UIGestureRecognizerViewController.h"

#define vc_title @"Gesture"


@interface UIGestureRecognizerViewController ()

@property (nonatomic, strong)UILabel *stateLabel;
@property (nonatomic, strong)UIView  *gestureView;

/** * 初始化用户界面 */
- (void)initializeUserInterface;

/** * 初始化手势 */
- (void)initializeGestureRecognizer;

@end

@implementation UIGestureRecognizerViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self initializeUserInterface];
    [self initializeGestureRecognizer];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    // autolayout自动布局
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[_stateLabel]-0-|"
                                                                      options:0
                                                                      metrics:nil
                                                                        views:NSDictionaryOfVariableBindings(_stateLabel)]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[_stateLabel(==30)]"
                                                                      options:0
                                                                      metrics:nil
                                                                        views:NSDictionaryOfVariableBindings(_stateLabel)]];
}

#pragma mark - init

- (void)initializeUserInterface
{
    self.view.backgroundColor = [UIColor whiteColor];
    self.title = vc_title;

    [self.view addSubview:self.stateLabel];
    [self.view addSubview:self.gestureView];

}

- (void)initializeGestureRecognizer
{
    // 1、点击手势识别器

    UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    // 设置点击次数
    tapGesture.numberOfTapsRequired = 1;
    // 设置手指数量
    tapGesture.numberOfTouchesRequired = 1;
    // 添加手势
    [_gestureView addGestureRecognizer:tapGesture];

    // 2、长按手势识别器
    UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    [_gestureView addGestureRecognizer:longPressGesture];

    // 3、滑动手势识别器
    UISwipeGestureRecognizer *swipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    // 设置滑动方向:right、left、up、down
    swipeGesture.direction = UISwipeGestureRecognizerDirectionRight;
    [_gestureView addGestureRecognizer:swipeGesture];

    // 4、拖拽手势识别器
    UIPanGestureRecognizer *panPress = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    [_gestureView addGestureRecognizer:panPress];

    // 5、捏合手势识别器
    UIPinchGestureRecognizer * pinchPress = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    [_gestureView addGestureRecognizer:pinchPress];

    // 6、旋转手势识别器

    UIRotationGestureRecognizer * rotationPress = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(respondsToGestureRecognizer:)];
    [_gestureView addGestureRecognizer:rotationPress];

    // 手势识别器冲突
    [swipeGesture requireGestureRecognizerToFail:panPress]; // 如果冲突，执行后面的



}

#pragma mark - responds event

- (void)respondsToGestureRecognizer:(UIGestureRecognizer *)gesture
{
    // 点击手势识别器
    if ([gesture isKindOfClass:[UITapGestureRecognizer class]]) {
        UITapGestureRecognizer *tap = (UITapGestureRecognizer *)gesture;
        // state 属性：获取用户手势状态
        if (tap.state == UIGestureRecognizerStateBegan) {
            [_stateLabel setText:@"用户开始点击"];
        }else if (tap.state == UIGestureRecognizerStateEnded){
            [_stateLabel setText:@"用户点击结束"];
        }
    }

    // 长按手势识别器
    else if ([gesture isKindOfClass:[UILongPressGestureRecognizer class]]){
        UILongPressGestureRecognizer *longPress = (UILongPressGestureRecognizer *)gesture;
        if (longPress.state == UIGestureRecognizerStateBegan) {
            [_stateLabel setText:@"长按手势开始"];
        }else if (longPress.state == UIGestureRecognizerStateEnded){
            [_stateLabel setText:@"长按手势结束"];
        }
    }

    // 滑动手势识别器
    else if ([gesture isKindOfClass:[UISwipeGestureRecognizer class]]){
        UISwipeGestureRecognizer *swipePress = (UISwipeGestureRecognizer *)gesture;
        if (swipePress.state == UIGestureRecognizerStateBegan) {
            [_stateLabel setText:@"滑动手势开始"];
        }else if(swipePress.state == UIGestureRecognizerStateChanged){
            [_stateLabel setText:@"滑动手势滑动中"];
        }else if (swipePress.state == UIGestureRecognizerStateEnded){
            [_stateLabel setText:@"滑动手势结束"];
        }
    }

    // 拖拽手势识别器
    else if ([gesture isKindOfClass:[UIPanGestureRecognizer class]]){
        UIPanGestureRecognizer *pan = (UIPanGestureRecognizer *)gesture;

        // 声明一个静态的变量记录拖拽视图前时的中心点
        static CGPoint firstCenter;
        if (pan.state == UIGestureRecognizerStateBegan) {
            // 给firstCenter赋值
            firstCenter = self.view.center;
            [_stateLabel setText:@"拖拽手势开始"];
        }else if (pan.state == UIGestureRecognizerStateChanged){
            // 获取手势在某一个视图上的移动了多少
            CGPoint translation = [pan translationInView:self.view];
            _gestureView.center = CGPointMake(firstCenter.x + translation.x, firstCenter.y + translation.y);
            [_stateLabel setText:@"拖拽手势拖动中"];
        }else if (pan.state == UIGestureRecognizerStateEnded){
            // 更新静态变量firstCenter的值，供下次识别这个手势时使用
            firstCenter = _gestureView.center;
            [_stateLabel setText:@"拖拽手势结束"];
        }
    }

    // 捏合手势识别器
    else if ([gesture isKindOfClass:[UIPinchGestureRecognizer class]]){
        UIPinchGestureRecognizer * pinch = (UIPinchGestureRecognizer *)gesture;
        static CGFloat lastScale;
        if (pinch.state == UIGestureRecognizerStateBegan) {
            lastScale = pinch.scale;
            [_stateLabel setText:@" 捏合手势开始"];
        }else if (pinch.state == UIGestureRecognizerStateChanged){
            CGFloat changeScale = (pinch.scale - lastScale)/2 + 1;
            if (_gestureView.bounds.size.width < 100) { // 当视图<100,就不能再缩小
                return;
            }else{
                _gestureView.transform = CGAffineTransformScale(_gestureView.transform, changeScale, changeScale);
                lastScale = pinch.scale;
            }
        }else if (pinch.state == UIGestureRecognizerStateEnded){
            lastScale = 1;
            [_stateLabel setText:@" 捏合手势结束"];
        }
    }

    // 旋转手势识别器
    else if ([gesture isKindOfClass:[UIRotationGestureRecognizer class]]){
        UIRotationGestureRecognizer * rotation = (UIRotationGestureRecognizer *)gesture;
        static CGFloat lastRotate;
        if (rotation.state == UIGestureRecognizerStateBegan) {
            lastRotate = rotation.rotation;
            [_stateLabel setText:@"旋转手势开始"];
        }else if (rotation.state == UIGestureRecognizerStateChanged){
            CGFloat changeRotate = rotation.rotation - lastRotate;
            _gestureView.transform = CGAffineTransformRotate(_gestureView.transform, changeRotate);
            lastRotate = rotation.rotation;
        }else if(rotation.state){
            lastRotate = 0;
        }
    }

}

#pragma mark - getter

- (UILabel *)stateLabel
{
    if (!_stateLabel) {
        _stateLabel = [[UILabel alloc] init];
        _stateLabel.translatesAutoresizingMaskIntoConstraints = NO;
        _stateLabel.textAlignment = NSTextAlignmentCenter;
        _stateLabel.font = [UIFont systemFontOfSize:25];
    }
    return _stateLabel;
}

- (UIView *)gestureView
{
    if (!_gestureView) {
        _gestureView = [[UIView alloc] init];
        _gestureView.bounds = CGRectMake(0, 0, 200, 200);
        _gestureView.center = self.view.center;
        _gestureView.backgroundColor = [UIColor redColor];
        // 开启用户交互
        _gestureView.userInteractionEnabled = YES;
    }
    return _gestureView;
}
@end