##Understanding of storyboard files
- Used to describe the software interface
- By default, Main.storyboard loads as soon as the program starts
- When loading storyboard, the controller interface pointed by the arrow is first created and displayed
## IBAction and IBOutlet
– IBAction：
- The essence is void
- Can enable the method to have connection functions
– IBOutlet
- Can make attributes have connection functions
###Problems that are prone to occur with storyboard connections
- The connection method code was deleted, but the connection was not removed
- Error may occur when the method cannot be found
– unrecognized selector sent to instance
- The attribute code of the connection was deleted, but the connection was not removed
– setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key
##Understanding of UIViewController
- One controller is responsible for managing a large interface
- The controller is responsible for interface creation, event processing, etc.
##Class Extension
- Format
“`objc
@interface class name ()
/** Declaration of attributes and methods */
@end
“`
- Role
- Add additional property and method declarations to a class
- Can be written in.h and.m files
##Project Properties
– Product Name
- Software name, product name, project name
– Organization Name
- Company name, organization name
– Organization Identifier
- Unique identification of the company
- Generally it is a reverse of the company's domain name, such as com.520it
– Bundle Identifier
- Unique identification of the software
- Generally Organization Identifier + Product Name