A process for querying and calling properties, methods, and subscripts on an optional that might currently be nil .Multiple queries can be chained …

A deinitializer is called immediately before a class instance is deallocated.

Initialization is the process of preparing an instance of a class, structure or enumeration for use.

Class A inherit from class B. Then A is the so call subclass, B is the superclass.

A shortcut for accessing the member of a collection, list, or sequence.

PART I: 失败的尝试为了能在手机端玩耍亚服原神，申请了一张JCB信用卡。填写材料还算顺利，但最初缺失败了，商店是日语了，但无奈购买。提醒说转区后订阅会生效，而敌人预先才说转区的时候不能有失效的订阅。起初我查了下，账号里还在失效的订阅服务只有一个，22号到期。连忙勾销，6天后再试一次PART II: 未完待续

MethodMethods are functions that associated with a particular type.Classes, structures and enumerations.Define instance methods for an instance of the given type.Define type method for the type itself.Instance MethodIt is defined in a type. And it can only be called by a specific instance of the …

Usually associated with instance of a particular type, can be associated with the type itself(type properties).

Objective-C语言里的分号（；）、花括号（｛｝）、方括号（［］）、圆括号(())、空格、圆点（.）都具备非凡的分隔作用，因而被统称为分隔符。

Structures and classes are the basic building blocks of the program’s code.