OBJECTIVE-C (Foundation framework One NSNumber (Nsvalue))

NSNumber: is a class that handles numbers in OC

Nsvalue is a subclass of NSNumber

How to handle:

Wrap the int,float,double into an object

Benefits of using NSNumber:

You can save data of a basic data type to an array or dictionary

// define basic data types
        int a = 10;
        float b = 2.2f;
        double d = 1.22;
        
        int x = 100;
       
        // int is wrapped as NSNumber
        NSNumber * intObj = [NSNumber numberWithInt: a];
        NSMutableArray * array = [NSMutableArray arrayWithObjects: intObj, nil];
        
        // float is wrapped into NSNumber
        NSNumber * floatObj = [NSNumber numberWithFloat: b];
        // add objects to the array
        [array addObject: floatObj];
        
        // double is wrapped into NSNumber
        NSNumber * doubleObj = [NSNumber numberWithDouble: d];
        // add objects to the array
        [array addObject: doubleObj];
        
        // @ 值 ， Wrap values into objects, a quick and easy way
        [array addObject: @ (x)];
        NSLog (@ "% @", array);
        
        // Add the first and second elements of the array
        NSNumber * n1 = array [0]; // remove the 0th element
        int a1 = [n1 intValue];
        NSNumber * n2 = array [1]; // remove the first element
        float a2 = [n2 floatValue];
        
        // a1 = a1 + a2;
        // concise
        a1 = [array [0] intValue] + [array [1] floatValue];
        NSLog (@ "% d", a1); 

Nsvalue: Mainly used to wrap pointers, cgrect structures, etc. into OC objects for storage

CGPoint p1 = CGPointMake (3, 5);
     CGRect r1 = CGRectMake (0, 3, 5, 9);
     NSMutableArray * arr = [NSMutableArray array];
     // p1 is wrapped into obj
     NSValue * pointValue = [NSValue valueWithPoint: p1];
    
     // Store objects in an array
     [arr addObject: pointValue];
     // wrap r1 into NSValue object
     [arr addObject: [NSValue valueWithRect: r1]];
     NSLog (@ "% @", arr);
    
     // take out the value of r1
     NSValue * r1Value = [arr lastObject];
     NSRect r2 = [r1Value rectValue];
    
     NSLog (@ "% @", NSStringFromRect (r2));

Packaging struct

// define date structure
typedef struct Date
{
     int year;
     int month;
     int day;
    
} MyDate;
int main (int argc, const char * argv []) {
     @autoreleasepool {
         // year month day
         MyDate nyr = {2015, 9, 11};
        
         // @encode (MyDate) function, generate a constant string description of the MyDate type
         NSValue * val = [NSValue valueWithBytes: & nyr objCType: @encode (MyDate)];
        
         // define an array and store val in it
         NSMutableArray * arr = [NSMutableArray arrayWithObject: val];
         / *
          Remove NSValue object from the array
          From the object, get the value of the structure variable
          Pass the address of a structure variable
          * /
         MyDate tmd;
         [val getValue: & tmd];
         NSLog (@ "% d,% d.% D", tmd.year, tmd.month, tmd.day); 

OBJECTIVE-C (Foundation framework One NSNumber (Nsvalue))