20th: Prefix the private method name

The private method name plus some prefixes,

1, help debugging;

2, it is easy to distinguish between public and private methods (that is, easy to distinguish which methods are easy to change, which are not easy to change.) ）。

Objective-c language There is no way to label a method private.

Each object can respond to any message (see 12), and it can view the messages that an object can respond to at run time (see article 14). Based on the given message, the corresponding method is identified, which is to be completed at run time (see article 11) (Objective-c language Dynamics , dynamic method distribution System Dispatch System)).

"P_" is the prefix for the private method name.

Do not prefix a private method with an underscore, as this is reserved for Apple.

Example:-(void) _resetviecontroller is the private method of Apple Uiviewcontroller, which resets all the States in the controller.
If you overwrite in a subclass, then the parent class will never execute, so the behavior of this view controller will be strange, and you may wonder why the methods of subclasses are called so frequently.

20th: Prefix the private method name