Dark Horse programmer--"Dark Horse Video Notes" description method of OC Language Foundation

General usefulness of the 1.description method

   1:  //address of the pointer variable

   2:      NSLog (@ "%p", &p);

   3:      //Address of Object

   4:      NSLog (@ "%p", p);

   5:      //< Class Name: Object address >

   6:      NSLog (@ "%@", p);

   1:  class];

   2:      

   3:      //1. The +description method that invokes the class

   4:      //2. Get the return value of the +description method (NSString *) displayed on the screen

   5:      NSLog (@ "%@", c);

Java-like ToString ()

2, the general use of description method attention points

   1:  //By default, when using NSLog and%@ output objects, the result is:< class name: Memory address >

   2:      

   3:      //1. The-description method that invokes the object P

   4:      //2. Get the return value of the-description method (NSString *) displayed on the screen

   5:      //The 3.-description method returns "class name + memory address" by default

   6:      NSLog (@ "%@", p);

   7:      

   8:      //person *p2 = [[Person alloc] init];

   9:      //nslog (@ "%@", p2);

  10:      

One   :      //nsstring *name = @ "Rose";

  12:      

  :      //nslog (@ "My name is%@", name);

  14:      

  :  person    *p2 = [[Person alloc] init];

  :      p2.age = 25;

  :      @ "Jake";

  18:      

  :      NSLog (@ "%@", p2);

3. Usage of the Description method

   1:  //determines the output of the instance object

   2:  //-(NSString *) Description

   3:  //{

   4:  ////The    following code will cause a dead loop

   5:  ////    NSLog (@ "%@", self);

   6:  //    return [NSString stringwithformat:@ "age=%d, name=%@", _age, _name];

   7:  //    //return @ "3424324";

   8:  //}

   9:  

  Ten:  //determines the output of the class object

One   :  + (NSString *) description

  :  {

  :      return@ "ABC";

  :  }

Dark Horse programmer--"Dark Horse Video Notes" description method of OC Language Foundation