The syntax specific to the last OC

Note: (because there is no apple around the first summary, the relevant code after the complement) three, description method1.-descriotion Method

When you use NSLog and%@ to output an object, the object's -description method is called and the return value is returned for output .

2.+description Method

When you use NSLog and %@ to output a class object, the Class object +description method is called, and the return value is obtained for output

3. Modify the default output of the NSLog

Rewrite the -description or +description method.

4. Dead Loop traps

If you use NSLog in the -description method, print self .

Iv. SEL1. Where to store the method

The list of methods for each class is stored in the class object

Each method has an object of the corresponding SEL type

The address of the method can be found based on a Sel object, and the method is called

Definition of SEL type

typedef struct OBJC_SELECTOR *sel;

Creation of 2.SEL objects

SEL s = @selector (test);

SEL s2 = nsselectorfromstring (@ "Test")

3.SELother uses of the object

Convert Sel object to NSString Object

NSString *str = Nsstringfromselector (@selector (test));

Person *p = [person new];

Call the test method of the object P

[P Performselector: @selector (test)];

The syntax specific to the last OC