objective-C学习 KVC

#import <Foundation/Foundation.h>

#import "Book.h"

int main(int argc,constchar * argv[]) {

    @autoreleasepool {

        // insert code here...

        

        

        Book *book = [[Bookalloc]init];

        

//        //键值访问

//        [book setValue:@"jianguo" forKey:@"_name"];   //KVC设置

//        NSString *name = [book valueForKey:@"_name"];     //KVC访问

//        NSLog(@"name = %@",name);

//        

//        //路径访问

//        Author *author = [[Author alloc]init];

//        [author setValue:@"yihong" forKey:@"_name"];

//        [book setValue:author forKey:@"_author"];

//        

//        NSString *authorName = [book valueForKeyPath:@"_author._name"];  //访问路径

//        NSLog(@"authorName = %@",authorName);

//        

//        [book setValue:@"longfeng" forKeyPath:@"_author._name"];

//        NSString *authorName2 = [book valueForKeyPath:@"_author._name"];  //访问路径

//        NSLog(@"authorName2 = %@",authorName2);

        

        //一对多

        NSMutableArray *reBook = [NSMutableArrayarrayWithCapacity:3];

        

        for (int i=0; i<3; i++) {

            Book *book = [[Bookalloc]init];

            NSString *names = [NSStringstringWithFormat:@"job_%d",i];

            [book setValue:names forKey:@"_name"];

            [book setValue:@(12+i)forKey:@"price"];

            [reBook addObject:book];

            [book release];

        

        }

        NSLog(@"reBook = %@",reBook);

        [book setValue:reBook forKey:@"reArray"];

        

//        NSArray *names = [book valueForKeyPath:@"reArray._name"];

        NSArray *names = [reBook valueForKeyPath:@"_name"];   //同上

        NSLog(@"names = %@",names);

        

        //运算 count,sum,max,min,avg

        [book setValue:[NSNumbernumberWithFloat:3.4]forKey:@"price"];

        float fl =[[book valueForKey:@"price"] floatValue];

        NSLog(@"price = %f",fl);

        

        NSString *sum = [book valueForKeyPath:@"[e-mail]"];

        NSLog(@"sum = %@",sum);

        

        NSString *max = [book valueForKeyPath:@"[e-mail]"];

        NSLog(@"max = %@",max);

        

        NSString *avg = [book valueForKeyPath:@"[e-mail]"]; //平均值

        NSLog(@"avg = %@",avg);

        

    }

    return 0;

}

Book.h

#import <Foundation/Foundation.h>

#import "Author.h"

@interface Book : NSObject{

@private

    NSString *_name;

    Author *_author;

    NSArray *reArray;

    

    float price;

}

@end

Book.m

#import "Book.h"

@implementation Book

@end

Author.h

#import <Foundation/Foundation.h>

@interface Author : NSObject{

@private

    NSString *_name;

}

@end

Author.m

#import "Author.h"

@implementation Author

@end