Deconstruct Hello objective-C program Reading Notes

Numeric value to boolean type,1. nsstring contains many features. For example, it can be directly converted to the numeric type (integer or floating point type)

 

1Nsstring * test =@"This is my name";

2 If (Nsorderedascending = [test compare: @" This is my name 2 " ]) {
3 Nslog ( @" Appreciation " );
4 }
5 Nsstring * floatvaluestring = @" 12 " ;
6

7Nslog (@"% D floatvalue is % F", [Test length], [floatvaluestring floatvalue]);

 

2. How to Use nslog to output bool-type values.

Bool isbool = yes;

Nslog (@"% @", Isbool = Yes?@"Yes":@"No");  

 

3. You can assign an integer value to the bool type. The output result is"

Numeric value to boolean, 14"

Bool canacceptdigital =14;

Nslog (@"Numeric value to boolean, % d", Canacceptdigital );

 

4. In objective-C, Yes indicates 1, and no indicates 0.

1 If(2){

2 Nslog ( @" 2 can be executed " );
3 Nslog ( @" Yes is % d " , Yes );
4 Nslog ( @" No is % d " , No );

5} 

 

The output is as follows:

21:12:04. 763 Lookbook [791: 207]2 can be executed

21:12:04. 773 Lookbook [791: 207] Yes is 1 21:12:04. 778 Lookbook [791: 207] No is 0

 

5. Use % @ in nslog to output the definition in the description function of the object.

Header file: person. h

1 # Import <Foundation/Foundation. h>
2
3
4 @ Interface Person: nsobject {
5
6 }
7 -(Nsstring *) description;

8 @ End 

Implement file person. m

 # Import "Person. h"
@ Implementation Person
-(Nsstring *) Description
{
Return @" My name is description " ;
}

@ End  

Add the following method to viewdidload:

-( Void ) Viewdidload {
[Super viewdidload];

Person * D = [[person alloc] init];
Nslog (@"Person's description is % @", D );

}  

The result is as follows:

Person's description is my name is description

The next chapter, basic knowledge of object-oriented programming, is to be continued. Coming soon!