main.m(传值与引用)

#import <Foundation/Foundation.h>
#import "Observer.h"
#import "Person.h"
#import "Computer.h"
int main(int argc, const char * argv[]) {
    @autoreleasepool {
/*
        Person *per = [[Person alloc]init];
//        Computer *computer1 = [[Computer alloc]init];
//        per.computer = [computer1 autorelease];
//        [per release];

        per.name = [NSString stringWithFormat:@"abc"];//retaincount = 2
        per.name = [NSString stringWithFormat:@"bcd"];//2
        per.name = nil;//没有

        //对象的内存什么时候释放？
        */
        Observer *ob = [[Observer alloc]init];

        NSArray *array = @[@"keyword"];

        [array writeToFile:@"/Users/wangzheng/Desktop/classSeven.txt" atomically:YES];

        NSArray *array1 = [NSArray arrayWithContentsOfFile:@"/Users/wangzheng/Desktop/classSeven.txt"];
        NSLog(@"%@",array1);
        //NSUserDefaults
        [[NSUserDefaults standardUserDefaults]setObject:@"12345" forKey:@"account"];//将数据存入本地路径（移动设备路径）
        BOOL succeed = [[NSUserDefaults standardUserDefaults]synchronize];

   //获取到Document和Library
        NSString *account = [[NSUserDefaults standardUserDefaults]objectForKey:@"account"];

        NSLog(@"%@",account);
  //数据持久化
        //对象归档  NSKeyedArchiver NSKeyedUnarchiver
       //网络请求  服务器
       // 云  icloud

        NSLog(@"Hello, World!");
    }
    return 0;
}