Teacher *t = [Teacher alloc ] init];
t.chiild = [Child alloc ] init];
t.child.book = [Book alloc] init];
XBLog(@"%@",ValueForKeyPath(@"child.book"));

import UIKit

//属性前加上@objc dynamic实现动态派发
class Preson: NSObject {
    @objc dynamic var age = 0
}

class ViewController: UIViewController {

    let p = Preson()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        //为p对象的age属性设置监听。
        //options为枚举数组，传入了new和old两个值，表示我们需要监听改变前和改变后的值。
        //context是Any类型，可以传入任意类型数据，方便在监听到变化时获取该数据。
        p.addObserver(self, forKeyPath: "age", options: [.new, .old], context: nil)
    }
    
    //监听
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "age" {
            print("age被改变了")
            print(change as Any)
        }
    }
    
    //释放监听
    deinit { 
        p.removeObserver(self, forKeyPath: "age")
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        p.age = 20
    }

}

2019-07-17 11:38:19.396278+0800 Homecare[10181:3941027] CredStore - performQuery - Error copying matching creds.  Error=-25300, query={
    class = inet;
    "m_Limit" = "m_LimitAll";
    ptcl = htps;
    "r_Attributes" = 1;
    sdmn = Users;
    srvr = "cloud.demo.cn";
    sync = syna;
}

init() {
    //关闭认证
    let configuration = URLSessionConfiguration.default
    configuration.httpAdditionalHeaders = Alamofire.SessionManager.defaultHTTPHeaders
    configuration.urlCredentialStorage = nil
    
    let policies: [String: ServerTrustPolicy] = [
        "cloud.demo.cn": .disableEvaluation
    ]
    
    super.init(configuration: configuration,serverTrustPolicyManager: ServerTrustPolicyManager(policies: policies))
}

let subView = UIView()
let left = NSLayoutConstraint(item: videoView, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0)
let right = NSLayoutConstraint(item: videoView, attribute: .right, relatedBy: .equal, toItem: view, attribute: .right, multiplier: 1, constant: 0)
let top = NSLayoutConstraint(item: videoView, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 0)
let bottom = NSLayoutConstraint(item: videoView, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0)
let constraints = [left, right, top, bottom]
NSLayoutConstraint.activate(constraints)

let subView = UIView()
subview.translatesAutoresizingMaskIntoConstraints = false
.......

2019-07-23 09:26:33.044872+0800 Homecare[5571:122357] Task <5547B0FE-DA52-400E-AF8E-D97453C9F2B0>.<1> finished with error - code: -1022
2019-07-23 09:26:33.046236+0800 Homecare[5571:122356] Task <5547B0FE-DA52-400E-AF8E-D97453C9F2B0>.<1> load failed with error Error Domain=NSURLErrorDomain Code=-1022 "The resource could not be loaded because the App Transport Security policy requires the use of a secure connection." UserInfo={NSLocalizedDescription=The resource could not be loaded because the App Transport Security policy requires the use of a secure connection., NSErrorFailingURLStringKey=http://undefined/rest/things, NSErrorFailingURLKey=http://undefined/rest/things, _NSURLErrorRelatedURLSessionTaskErrorKey=(
    "LocalDataTask <5547B0FE-DA52-400E-AF8E-D97453C9F2B0>.<1>"
), _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <5547B0FE-DA52-400E-AF8E-D97453C9F2B0>.<1>, NSUnderlyingError=0x600003f18b10 {Error Domain=kCFErrorDomainCFNetwork Code=-1022 "(null)"}} [-1022]

class aViewController {
	override func viewDidLoad() {
    	super.viewDidLoad()
        
        let vc = bTabelViewController()
        view.addsubView(vc.view)
    }
}

let startPoint = mapView.convert(start.coordinate, toPointTo: mapView)
let endPoint = mapView.convert(end.coordinate, toPointTo: mapView)
......
self.view.layer.addSublayer(lineLayer)

let startPoint = mapView.convert(start.coordinate, toPointTo: view)
let endPoint = mapView.convert(end.coordinate, toPointTo: view)
......
self.view.layer.addSublayer(lineLayer)

   //背景设置为空
self.navigationController?.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .Default)
   //去除横线
   self.navigationController?.navigationBar.shadowImage = UIImage()
   //设置为透明
   self.navigationController?.navigationBar.isTranslucent = true

func scrollViewDidScroll(_ scrollView: UIScrollView) {

    let offset = scrollView.contentOffset.y
    //大标题模式下的数值
    if offset <= -88 {
        naviAlpha = 0
    } else if offset < -22 {
        naviAlpha = (offset+88)/64
    } else {
        naviAlpha = 1
    }
    let image = UIImage.imageWithColor(Colors.naviBackground.withAlphaComponent(naviAlpha))
    navigationController?.navigationBar.setBackgroundImage(image, for: .default)
}