如何將double類型轉換爲CGAffineTransform？

Question

當我旋轉我的形象的看法：

func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) { 
    imageView?.transform = newHeading.trueHeading 

} 

我得到以下錯誤：

Cannot assign value of type 'CLLocationDirection' (aka 'Double') to type 'CGAffineTransform'

如何轉換/分配呢？

UPDATE：

一切編譯好了，但是當我在模擬器中運行我的應用程序（我沒有任何iOS設備），我的ImageView的不是真北旋轉。

爲什麼？

import UIKit 
import CoreLocation 

class ViewController: UIViewController,CLLocationManagerDelegate { 

    var manager: CLLocationManager? 
    var imageView: UIImageView? 

    override func viewDidLoad() { 
     super.viewDidLoad() 
     // Do any additional setup after loading the view, typically from a nib. 
     manager = CLLocationManager() 
     manager?.delegate = self; 
     manager?.desiredAccuracy = kCLLocationAccuracyBest 


     imageView = UIImageView(image:#imageLiteral(resourceName: "pointer")) 
     self.view.addSubview(imageView!) 

    } 
    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 
    func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) { 
     imageView?.transform = CGAffineTransform(rotationAngle: CGFloat(newHeading.trueHeading)) 

    } 

} 

Answer 1

trueHeading是以度Double類型。

爲了旋轉UIImageView，一個必須提供的變換：

func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) 
{ 
    imageView?.transform = CGAffineTransform(rotationAngle: CGFloat(newHeading.trueHeading * .pi/180)) 
    // converting the value from degrees to radians, which CGAffineTransform expects. 
}