[移动开发]swift 单指旋转图片，超简单（已封存，开箱即用）

工具类：

//  Created by hdf on 2022/3/31.

import UIKit

class UIOneFingerRotationGes: UIGestureRecognizer {

    var rotation: CGFloat = 0.0
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        if (event.touches(for: self)?.count ?? 0) > 1 {
            self.state = .failed
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        if self.state == .possible {
            self.state = .began
        } else {
            self.state = .changed
        }
        
        guard let touch = touches.first, let view = self.view else { return }
        let center = CGPoint(x: view.bounds.midX, y: view.bounds.midY)
        let currentTouchPoint = touch.location(in: view)
        let previousTouchPoint = touch.previousLocation(in: view)
        
        let f1 = Float(currentTouchPoint.y - center.y)
        let f2 = Float(currentTouchPoint.x - center.x)
        let f3 = Float(previousTouchPoint.y - center.y)
        let f4 = Float(previousTouchPoint.x - center.x)
        let angle = atan2f(f1, f2) - atan2f(f3, f4)
        self.rotation = CGFloat(angle)
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        if state == .changed {
            state = .ended
        } else {
            state = .failed
        }
    }
    
    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {
        state = .cancelled
    }
    
}

使用方法：

let oneRotate = UIOneFingerRotationGes(target: self, action: #selector(oneFingerRotateAction(ges:)))        
compassImgV.addGestureRecognizer(oneRotate)

   @objc private func oneFingerRotateAction(ges: UIOneFingerRotationGes) {
        compassImgV.transform = compassImgV.transform.rotated(by: ges.rotation)
    }