导入头文件

#import <CallKit/CXCallObserver.h>
#import <CallKit/CXCall.h>

在需要的地方调用拨打电话方法,在 openURL的回调里,实例化CXCallObserver并设置代理,同时设置回调的队列

//拨打电话
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"telprompt://10086"] options:@{} completionHandler:^(BOOL success) {
        NSLog(@"%d",success);
        if(!success) return ;
        //设置电话代理
        _callObserver = [[CXCallObserver alloc]init];
        [_callObserver setDelegate:self queue:dispatch_get_main_queue()];
    }];

实现CXCallObserver的代理方法,根据 call 返回的信息 判断电话处于什么状态,根据不同状态搞不同的事情

-(void)callObserver:(CXCallObserver *)callObserver callChanged:(CXCall *)call{
    
    NSLog(@"outgoing :%d  onHold :%d   hasConnected :%d   hasEnded :%d",call.outgoing,call.onHold,call.hasConnected,call.hasEnded);
    /** 以下为我手动测试 如有错误欢迎指出
      拨通:  outgoing :1  onHold :0   hasConnected :0   hasEnded :0
      拒绝:  outgoing :1  onHold :0   hasConnected :0   hasEnded :1
      链接:  outgoing :1  onHold :0   hasConnected :1   hasEnded :0
      挂断:  outgoing :1  onHold :0   hasConnected :1   hasEnded :1
     
      新来电话:    outgoing :0  onHold :0   hasConnected :0   hasEnded :0
      保留并接听:  outgoing :1  onHold :1   hasConnected :1   hasEnded :0
      另一个挂掉:  outgoing :0  onHold :0   hasConnected :1   hasEnded :0
      保持链接:    outgoing :1  onHold :0   hasConnected :1   hasEnded :1
      对方挂掉:    outgoing :0  onHold :0   hasConnected :1   hasEnded :1
     */
    //接通
    if (call.outgoing && call.hasConnected && !call.hasEnded) {
          //记录当前时间
        _beforeDate = [NSDate date];
    }
    //挂断
    if (call.outgoing && call.hasConnected && call.hasEnded) {
  //计算通话时长   
    NSDate* dat = [NSDate dateWithTimeInterval:0 sinceDate:_beforeDate];
    NSTimeInterval a=[dat timeIntervalSinceNow];
    NSString *timeString = [NSString stringWithFormat:@"%0.f",fabs(a)];//转为字符型
    NSLog(@"%@秒",timeString); 
    }
}

防止意外,在控制器销毁时 把 delegate 设为 nil

-(void)dealloc{
    [_callObserver setDelegate:nil queue:dispatch_get_main_queue()];
    _callObserver = nil;
}

注意:

如果代理回调没有执行
1.查看是否设置代理
2.需要把callObserver 全局引用,保证不销毁.
3.以上方法为10.0之后 需要判断 版本再10.0之前使用

        //获取通话状态
            _callCenter.callEventHandler =  { (call: CTCall) -> Void in
                if call.callState == CTCallStateDisconnected {
                  print("挂断电话")
                   self.callStateDisconnected()
                }
                if call.callState == CTCallStateConnected {
                    print("电话接通")
                      self.beforeDate = NSDate()
                }
                if call.callState == CTCallStateIncoming {
                    print("通话途中收到别的来电")
                }
                if call.callState == CTCallStateDialing {
                    print("电话播出")
                }