在来电中恢复AVAudioRecorder的解决方法如下：

1. 监听来电状态变化，可以使用CoreTelephony框架来实现。在电话接通和挂断时，会触发相应的通知，我们可以在通知的回调方法中暂停和恢复录音。

import AVFoundation
import CoreTelephony

class ViewController: UIViewController {
    var audioRecorder: AVAudioRecorder?
  
    override func viewDidLoad() {
        super.viewDidLoad()
    
        // 监听电话状态变化
        NotificationCenter.default.addObserver(self, selector: #selector(handleCallStateChange), name: NSNotification.Name.CTCallStateDidChange, object: nil)
        
        // 设置录音会话
        let session = AVAudioSession.sharedInstance()
        do {
            try session.setCategory(.playAndRecord, mode: .default, options: [])
            try session.setActive(true)
        } catch {
            print("Failed to set audio session: \(error.localizedDescription)")
        }
        
        // 初始化AVAudioRecorder
        let audioFilename = getDocumentsDirectory().appendingPathComponent("recording.wav")
        let settings = [
            AVFormatIDKey: Int(kAudioFormatLinearPCM),
            AVSampleRateKey: 44100.0,
            AVNumberOfChannelsKey: 2,
            AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
        ]
        
        do {
            audioRecorder = try AVAudioRecorder(url: audioFilename, settings: settings)
            audioRecorder?.prepareToRecord()
        } catch {
            print("Failed to initialize audio recorder: \(error.localizedDescription)")
        }
    }
    
    @objc func handleCallStateChange(notification: NSNotification) {
        guard let call = CTCallCenter().currentCalls.first else { return }
        
        if call.callState == CTCallStateConnected {
            // 来电接通，暂停录音
            audioRecorder?.pause()
        } else if call.callState == CTCallStateDisconnected {
            // 来电挂断，恢复录音
            audioRecorder?.record()
        }
    }
    
    func getDocumentsDirectory() -> URL {
        let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return paths[0]
    }
}

上述代码中，我们在viewDidLoad方法中设置了录音会话，并初始化了AVAudioRecorder对象。在handleCallStateChange方法中，我们根据来电状态的变化来暂停和恢复录音。当电话接通时，我们调用pause方法暂停录音；当电话挂断时，我们调用record方法恢复录音。

请注意，为了监听来电状态变化，需要在项目中导入CoreTelephony.framework，并添加对CoreTelephony的引用。

2. 如果你使用SwiftUI来实现界面，可以使用onReceive修饰符来监听电话状态变化。

import AVFoundation
import CoreTelephony
import SwiftUI

class RecorderViewModel: ObservableObject {
    var audioRecorder: AVAudioRecorder?
  
    init() {
        // 监听电话状态变化
        NotificationCenter.default.addObserver(self, selector: #selector(handleCallStateChange), name: NSNotification.Name.CTCallStateDidChange, object: nil)
        
        // 设置录音会话
        let session = AVAudioSession.sharedInstance()
        do {
            try session.setCategory(.playAndRecord, mode: .default, options: [])
            try session.setActive(true)
        } catch {
            print("Failed to set audio session: \(error.localizedDescription)")
        }
        
        // 初始化AVAudioRecorder
        let audioFilename = getDocumentsDirectory().appendingPathComponent("recording.wav")
        let settings = [
            AVFormatIDKey: Int(kAudioFormatLinearPCM),
            AVSampleRateKey: 44100.0,
            AVNumberOfChannelsKey: 2,
            AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
        ]
        
        do {
            audioRecorder = try AVAudioRecorder(url: audioFilename, settings: settings)
            audioRecorder?.prepareToRecord()
        } catch {
            print("Failed to initialize audio recorder: \(error.localizedDescription)")
        }
    }
    
    @objc func handleCallStateChange(notification: NSNotification) {
        guard let call = CTCallCenter().currentCalls.first else { return }
        
        if call.callState == CTCallStateConnected {
            // 来电接通，暂停录音
            audioRecorder?.pause()
        } else if call.callState