11. Gesture recognition

Gesture recognition

1、 Gesture type

iOS Provides 7 Three common gestures API, Include Tap( single click ),Long Press( Long press ),Pan( translation ),Swipe( slide ),Rotation( rotate ),Pinch( The closing and opening of fingers ), and Screen Edge Pan( Screen edge pan )

2、 Gesture recognizer

stay iOS There are two ways to recognize gestures on the device ： Use gesture recognizer （UIGestureRecognizer） And touch events （UITouch）
Gesture recognizer is an abstract class , But it has seven concrete classes ：

• UITapGestureRecognizer
• UIPinchGestureRecognizer
• UIRotationGestureRecognizer
• UISwipeGestureRecognizer
• UIPanGestureRecognizer
• UILongPressGestureRecognizer
• UIScreenEdgePanGestureRecognizer
  If these seven gesture recognizers can not meet the requirements , You can also inherit directly UIGestureRecognizer Realize your own special gesture recognition .

3、 Seven gesture code examples

1.Tap

import UIKit

class ViewController: UIViewController {
    
    
    // Set up flag
    var flag = false
    var imagegirl : UIImageView!
    var imagegirl1 : UIImage!
    var imagegirl2 : UIImage!

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let imageWidth:CGFloat = 90
        let imageHeight:CGFloat = 150
        let imageTopView:CGFloat = 300
        self.imagegirl = UIImageView(frame: CGRect(x: (screen.size.width - imageWidth)/2, y: imageTopView, width: imageWidth, height: imageHeight))
        
       // Set up imagegirl1 and 2 Properties of , And set the initial picture to girl_01
        self.imagegirl1 = UIImage(named: "girl_01")
        self.imagegirl2 = UIImage(named: "girl_02")
        self.imagegirl.image = self.imagegirl1
        // Add parent view 
        self.view.addSubview(self.imagegirl)
        
        // Create a gesture recognizer 
        let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(foundTap(_:)))
        
        // take Tap The gesture recognizer is associated with iamgegirl On 
        self.imagegirl.addGestureRecognizer(tapRecognizer)
        self.imagegirl.isUserInteractionEnabled = true
        
        

    }
    @objc func foundTap(_ sender:AnyObject){
    
        
        print("Tap…")
        if flag {
    
            self.imagegirl.image = imagegirl2
            flag = false
        }else{
    
            self.imagegirl.image = imagegirl1
            flag = true
        }
    }

}

2.Long Press

import UIKit

class ViewController: UIViewController {
    
    
    // Set up flag
    var flag = false
    var imagegirl : UIImageView!
    var imagegirl1 : UIImage!
    var imagegirl2 : UIImage!

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let imageWidth:CGFloat = 90
        let imageHeight:CGFloat = 150
        let imageTopView:CGFloat = 300
        self.imagegirl = UIImageView(frame: CGRect(x: (screen.size.width - imageWidth)/2, y: imageTopView, width: imageWidth, height: imageHeight))
        
       // Set up imagegirl1 and 2 Properties of , And set the initial picture to girl_01
        self.imagegirl1 = UIImage(named: "girl_01")
        self.imagegirl2 = UIImage(named: "girl_02")
        self.imagegirl.image = self.imagegirl1
        // Add parent view 
        self.view.addSubview(self.imagegirl)
        
        // Create a gesture recognizer 
        let recognizer = UILongPressGestureRecognizer(target: self, action: #selector(foundLongPress(_:)))
        recognizer.allowableMovement = 100.0
        recognizer.minimumPressDuration = 2.0
        
        
        // take Tap The gesture recognizer is associated with iamgegirl On 
        self.imagegirl.addGestureRecognizer(recognizer)
        self.imagegirl.isUserInteractionEnabled = true
        
        

    }
    @objc func foundLongPress(_ sender:UITapGestureRecognizer){
    
        
        print(" Long press  state= ",sender.state.rawValue)
        if sender.state == .began{
     // The gesture begins 
            self.imagegirl.image = imagegirl2
            flag = false
        }else{
    
            self.imagegirl.image = imagegirl1
            flag = true
        }
    }

}

3.Pan

import UIKit

class ViewController: UIViewController {
    
    
    // Set up flag
    var flag = false
    var imagegirl : UIImageView!
    var imagegirl1 : UIImage!
    var imagegirl2 : UIImage!

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let imageWidth:CGFloat = 90
        let imageHeight:CGFloat = 150
        let imageTopView:CGFloat = 300
        self.imagegirl = UIImageView(frame: CGRect(x: (screen.size.width - imageWidth)/2, y: imageTopView, width: imageWidth, height: imageHeight))
        
       // Set up imagegirl1 and 2 Properties of , And set the initial picture to girl_01
        self.imagegirl1 = UIImage(named: "girl_01")
        self.imagegirl2 = UIImage(named: "girl_02")
        self.imagegirl.image = self.imagegirl1
        // Add parent view 
        self.view.addSubview(self.imagegirl)
        
        // Create a gesture recognizer 
        let recognizer = UIPanGestureRecognizer(target: self, action: #selector(foundPan(_:)))
        // Set the number of contacts in min max format 
        recognizer.minimumNumberOfTouches = 1
        recognizer.maximumNumberOfTouches = 1
        
        
        // take Tap The gesture recognizer is associated with iamgegirl On 
        self.imagegirl.addGestureRecognizer(recognizer)
        self.imagegirl.isUserInteractionEnabled = true
        
        

    }
    @objc func foundPan(_ sender:UIPanGestureRecognizer){
    
        
        print(" translation  state= ",sender.state.rawValue)
        if sender.state != .ended {
    
            // Return contact at imageView Coordinates in the parent view 
            let location = sender.location(in: sender.view?.superview)
            // Take the contact coordinates as imageView New center point location . Constantly changing imageView The location of , You will see the translation effect 
            sender.view?.center = location
        }
    }

}

4、Swipe

import UIKit

class ViewController: UIViewController {
    
    
    // Set up flag
    var flag = false
   /* var imagegirl : UIImageView! var imagegirl1 : UIImage! var imagegirl2 : UIImage! */
    var label:UILabel!

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let labelWidth:CGFloat = 100
        let labelHeight:CGFloat = 100
        let labelTopView:CGFloat = 270
        self.label = UILabel(frame: CGRect(x: (screen.size.width - labelWidth)/2, y: labelTopView, width: labelWidth, height: labelHeight))
        self.label.text = "Swipe gesture "
        self.label.textColor = .white
        self.label.textAlignment = .center
        self.view.addSubview(self.label)
       // Create four swipe Gesture recognizer 
        let directions:[UISwipeGestureRecognizer.Direction] = [.left,.right,.up,.down]
        
        for direction in directions {
    
            // Create a gesture recognizer 
            let recognizer = UISwipeGestureRecognizer(target: self, action: #selector(foundSwipe(_:)))
            recognizer.direction = direction
            // Associate a gesture recognizer to View On 
            self.view.addGestureRecognizer(recognizer)
        }
        self.view.isUserInteractionEnabled = true

    }
    @objc func foundSwipe(_ sender:UISwipeGestureRecognizer){
    
        
        print(" slide  direction= ",sender.state.rawValue)
        switch sender.direction {
    
        case .down:
            self.label.text = " Decline in "
        
        case .up:
            self.label.text = " Up slide "
       
        case .left:
            self.label.text = " Left slide "
        
        case .right:
            self.label.text = " Right slip "
        default:
            self.label.text = " Unknown "
        }
        
        
    }

}

5.Rotation

import UIKit

class ViewController: UIViewController {
    
    
   var imagegirl : UIImageView!
   var imagegirl1 : UIImage!
   // Used to save the last rotation angle 
    var rotationAngleInRadians:CGFloat = 0

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let imageWidth:CGFloat = 100
        let imageHeight:CGFloat = 150
        let imageTopView:CGFloat = 270
        self.imagegirl = UIImageView(frame: CGRect(x: (screen.size.width - imageWidth)/2, y: imageTopView, width: imageWidth, height: imageHeight))
        self.view.addSubview(imagegirl)
        
        imagegirl1 = UIImage(named: "girl_01")
        imagegirl.image = imagegirl1
        
        // Create a gesture recognizer 
        let recognizer = UIRotationGestureRecognizer(target: self, action: #selector(findRatation(_:)))
        // Associate gestures to imagegirl
        self.imagegirl.addGestureRecognizer(recognizer)
        // Set up imagegirl Open user event 
        self.imagegirl.isUserInteractionEnabled = true

    }
    @objc func findRatation(_ sender:UIRotationGestureRecognizer){
    
        print("Rattion……")
        self.imagegirl.transform = CGAffineTransform(rotationAngle: self.rotationAngleInRadians + sender.rotation)
        if sender.state == .ended {
    
            self.rotationAngleInRadians += sender.rotation
        }
}

}

6、Pinch

import UIKit

class ViewController: UIViewController {
    
    
   var imagegirl : UIImageView!
   var imagegirl1 : UIImage!
   // Used to save the scale size of the last zoom 
    var currentScale:CGFloat = 1.0

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set up imagegirl Size and properties of 
        let screen = UIScreen.main.bounds
        let imageWidth:CGFloat = 100
        let imageHeight:CGFloat = 150
        let imageTopView:CGFloat = 270
        self.imagegirl = UIImageView(frame: CGRect(x: (screen.size.width - imageWidth)/2, y: imageTopView, width: imageWidth, height: imageHeight))
        self.view.addSubview(imagegirl)
        
        imagegirl1 = UIImage(named: "girl_01")
        imagegirl.image = imagegirl1
        
        // Create a gesture recognizer 
        let recognizer = UIPinchGestureRecognizer(target: self, action: #selector(findPinch(_:)))
        // Associate gestures to imagegirl
        self.imagegirl.addGestureRecognizer(recognizer)
        // Set up imagegirl Open user event 
        self.imagegirl.isUserInteractionEnabled = true

    }
    @objc func findPinch(_ sender:UIPinchGestureRecognizer){
    
        print(" Zoom factor  = ",sender.scale)
        if sender.state == .ended {
    
            self.currentScale = sender.scale
        }else if sender.state == .began && currentScale != 0.0 {
    
            sender.scale = currentScale
        }
        self.imagegirl.transform = CGAffineTransform(scaleX: sender.scale, y: sender.scale)
}

}

7、Screen Edge Pan gesture

import UIKit

class ViewController: UIViewController {
    
    
   
    var label:UILabel!

    override func viewDidLoad() {
    
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // Set size and properties 
        let screen = UIScreen.main.bounds
        let labelWidth:CGFloat = 200
        let labelHeight:CGFloat = 150
        let labelTopView:CGFloat = 270
        self.label = UILabel(frame: CGRect(x: (screen.size.width - labelWidth)/2, y: labelTopView, width: labelWidth, height: labelHeight))
        self.label.text = " Screen edge gesture recognition "
        self.label.textColor = .white
        self.label.textAlignment = .center
        self.view.addSubview(self.label)
        // Create a gesture recognizer 
        let edges:[UIRectEdge] = [.right,.left]
        
        for edge in edges {
    
            let recognizer = UIScreenEdgePanGestureRecognizer(target: self, action: #selector(findScreenPan(_:)))
            // Set the direction of the screen edge translation 
            recognizer.edges = edge
            // Associate gestures to View
            self.view.addGestureRecognizer(recognizer)
        }
        // Set up imagegirl Open user event 
        self.view.isUserInteractionEnabled = true
        
        }
    override func didReceiveMemoryWarning() {
    
              super.didReceiveMemoryWarning()
       
    }
    @objc func findScreenPan(_ sender:UIScreenEdgePanGestureRecognizer){
    
        print("edge = ",sender.edges.rawValue)
        switch sender.edges {
    
        case UIRectEdge.right:
            self.label.text = " Shift left edge "
        case UIRectEdge.left :
            self.label.text = " Shift to the right edge "
        default:
            self.label.text = " Unknown direction "
        }
        
    }

}