Swift 遇到的坑

++++++++++++++++++
swift5中自适应文本中的高度，代码如下：

 let str = "测试测试";
 let rect = NSString(string: str).boundingRect(with: CGSize(width: UIScreen.main.bounds.size.width - 2 * 30, height: CGFloat(MAXFLOAT)), options: .usesFontLeading, attributes: [NSAttributedString.Key.font : UIFont.systemFont(ofSize: 14)], context: nil)

print("_______\(rect.size.width)")
print("________>>>>>>>>\(ceil(rect.width))")
        
打印结果
_______57.120000000000005
________>>>>>>>>58.0

在swift中字典转模型，创建的model 继承自 NSObject，如果是swift 3 ，则在模型中创建属性不需要前面加@objc，而在swift 4 中如果model中不添加@objc，则会出现属性赋值不进去
代码如下:


class AnchorGroupModel : NSObject {
    
    /*
     {
     "error": 0,
     "data": [
     {
     "icon_url": "https://cs-op.douyucdn.cn/dycatr/game_cate/d3e0073bfb714186ab0c818744601963.jpg",
     "small_icon_url": "https://cs-op.douyucdn.cn/dycatr/game_cate/ffdc72ed97b50ad8011de9a779b8d83b.png",
     "tag_name": "英雄联盟",
     "tag_id": "1",
     "push_vertical_screen": "0",
     "push_nearby": "0",
     "room_list": []
     },
     {},
     {},
     ]
     }
     */
    
    //该组中对应的房间信息 -- 数组也要加上objc
   @objc var room_list : [[String : NSObject]]?
    //组显示的标题
   @objc var tag_name : String = ""
    //组显示的图标
   @objc var icon_url : String = ""
    
    init(dict : [String : Any ]) {
        super.init()
        
        setValuesForKeys(dict)
    }
    
    override func setValue(_ value: Any?, forUndefinedKey key: String) {
        
    }

}

获取数据赋值,在swift 4 中，下面的self.anchorGroup是有值的，但是AnchorGroupModel的属性不加@objc，也不会打印出tag_name的值

extension RecommendViewModel {
    func requestData() {
        
        //请求推荐数据
        
        //请求颜值数据
        
        //请求游戏数据
        NetWorkTools.requestData(type: .GET, URLString: "http://capi.douyucdn.cn/api/v1/getHotCate", parameters: ["limit" : "4", "offset" : "0", "time" : NSDate.getCurrentTime() as NSString]) { (response) in
            
            print(response)
            
            guard let resultDic = response  as? [String : NSObject] else {
                
                return
            }
            
            guard let dataArray = resultDic["data"] as? [[String : Any]]  else {
                return
            }
            
            for dict in dataArray {
                
                let group = AnchorGroupModel(dict: dict)
                self.anchorGroup.append(group)
                
                let ss = self.anchorGroup.first
                
                print(ss?.tag_name ?? "rr")
                
                 print("+++gggggg++\(self.anchorGroup)")
            }
            
            for group in self.anchorGroup {
                
                print("++++++" + group.tag_name)
                print("++++++" + group.icon_url)
                
            }
        }
    }
}

添加全局的pop手势

实现方式：利用运行时机制，获取系统Pop手势target&action

获取系统的手势监听view
获取系统的手势target&action
创建自己的手势，添加事件监听时，使用上步中的target&action
将手势，添加到系统手势监听的view中

--------上代码-----------

利用运行时机制查看所有的属性名称

var count : UInt32 = 0
        let ivars = class_copyIvarList(UIGestureRecognizer.self, &count)!
        for i in 0..<count {
            let ivar = ivars[Int(i)]
            //name 是一个指针
            let name = ivar_getName(ivar)
            //指针转成字符串
            print("++++++++++++\(String(cString: name!))")
        }

打印出来的结果如下,我们使用到的就是_targets

/*
         ++++++++++++_gestureFlags
         ++++++++++++_targets
         ++++++++++++_delayedTouches
         ++++++++++++_delayedPresses
         ++++++++++++_view
         ++++++++++++_lastTouchTimestamp
         ++++++++++++_firstEventTimestamp
         ++++++++++++_state
         ++++++++++++_allowedTouchTypes
         ++++++++++++_initialTouchType
         ++++++++++++_internalActiveTouches
         ++++++++++++_forceClassifier
         ++++++++++++_requiredPreviewForceState
         ++++++++++++_touchForceObservable
         ++++++++++++_touchForceObservableAndClassifierObservation
         ++++++++++++_forceTargets
         ++++++++++++_forcePressCount
         ++++++++++++_beganObservable
         ++++++++++++_failureRequirements
         ++++++++++++_failureDependents
         ++++++++++++_activeEvents
         ++++++++++++_keepTouchesOnContinuation
         ++++++++++++_delegate
         ++++++++++++_allowedPressTypes
         ++++++++++++_name
         ++++++++++++_gestureEnvironment
         */

添加自己手势步骤如下：

//获取系统的pop手势
        guard let  systemGes = interactivePopGestureRecognizer else {
            return
        }
        
        //获取手势添加到的view 中
        guard let gesView = systemGes.view else {
            return
        }

 let targets = systemGes.value(forKey: "_targets") as? [NSObject]

 guard let targetObject = targets?.first else {
            return
        }
        
        //取出target
        guard let target = targetObject.value(forKey: "target") else {
            return
        }
       
        
        //取出action
        let action = Selector(("handleNavigationTransition:"))

        //创建自己pan手势
        let panGes  = UIPanGestureRecognizer()
        gesView.addGestureRecognizer(panGes)
        panGes.addTarget(target, action: action)

*********然后完美实现**********
----------------分哥线-----------------

image.png

问题：子类不能重写父类的extension的方法？怎么解决呢？
解决方法如下：

//父类中
@objc extension MOBBaseViewController {
    //要重写的方法
    public func testExt() {
        
        print("----------");
        
    }
    
}


-----
//子类中
import UIKit


class MOBClassifyViewController: MOBBaseViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    
    //重写父类extension方法
     override func testExt(){
        
        print(">>>>>>>>>>>>")
    }

}

因为extension中的方法是私有的，so子类访问不到，因此要用public修饰下，@objc有以下两点说明：

fileprivate 或者 private 保证方法私有能在同一个类或者同一个文件（extension）中访问这个方法如果定义为private 那么只能在一个类中访问不能在类扩展中访问
允许这个函数在“运行时”通过oc的消息机制调用

如果你去看某位大神写的swift 的Demo时下载了编译会报错如下：

屏幕快照 2019-04-28 下午1.43.44.png

问题的原因是swift版本导致的，解决方法如下：

pod 文件中，将HandyJSON不要指定版本进行pod更新，更新后，跑项目，如果还没成功再看什么错误
如果还有其他pod库中有三方报同样错误，可以按下面步骤修改

image.png

点击pod，然后会在右侧Target下面看到pod管理的各个库，然后对应三方库进行版本修改

image.png

改完之后运行，看下能否成功，亲测可以~