Swift 学习

swift和OC 项目使用

1 #pragma mark 修改 // MARK:
2 计算高度

extension String {
 func ga_heightForComment(fontSize:CGFloat, width:CGFloat, maxHeight:CGFloat) -> CGFloat {
     let font = UIFont.systemFont(ofSize: fontSize)
     let rect = NSString(string:self).boundingRect(with: CGSize(width:width, height:maxHeight), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
     //        return rect.height
     return ceil(rect.height)
     }
 } 

swift 语法

1 as as! as?

	// as
        // 从派生类转换为基类 向上转型
        let cat = Cat()
        let animal = cat as Animal
        
        // 消除二异 数值类型转换
        let num1 = 42 as CGFloat
        let num2 = 42 as Int
        let num4 = (42 / 2) as Double
        print("\(num4)")
        
        // 类型判断
        switch animal {
        case let cat as Cat:
            print("cat")
        case let dog as Dog:
            print("dog")
        default:
            break
        }
        
        // as! 强制转换 向下转型
        //        let asAnmail: Animal = Animal()
        let asAnmail: Animal = Cat()
        asAnmail.name = "cat"
        print("\(asAnmail.name)")
        let catLog = asAnmail as! Cat
        
        // as? 。但 as? 如果转换不成功的时候便会返回一个 nil 对象。成功的话返回可选类型值（optional），需要我们拆包使用
        let asasAnmail : Animal = Cat()
        if let cat = animal as? Cat {
            print("cat is not nil")
        } else {
            print("cat is nil")
        }

2 扩展

 // 结构体
    struct RunTimeKey {
        static let jkKey = UnsafeRawPointer.init(bitPattern: "JKKey".hashValue)
    }
        // 扩展属性
    var jkPro:String? {
        set {
            objc_setAssociatedObject(self, ExtionViewController.RunTimeKey.jkKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
        }
        get {
            return objc_getAssociatedObject(self,  ExtionViewController.RunTimeKey.jkKey) as? String
        }
    }

3 UnsafePointer 指针结构体

4 4种传值
github.com/LiuDao27/pu…

5 计算

func ga_heightForComment(fontSize:CGFloat, width:CGFloat, maxHeight:CGFloat) -> CGFloat {
        let font = UIFont.systemFont(ofSize: fontSize)
        let rect = NSString(string:self).boundingRect(with: CGSize(width:width, height:maxHeight), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
//        return rect.height
        return ceil(rect.height)
    }