objective-C学习 KVC

#import <Foundation/Foundation.h>

#import "Book.h"

int main(int argc,const
char * 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:@"reArray.@sum.price"];

NSLog(@"sum = %@",sum);

NSString *max = [book
valueForKeyPath:@"reArray.@max.price"];

NSLog(@"max = %@",max);

NSString *avg = [book
valueForKeyPath:@"reArray.@avg.price"]; //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