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目录：
一、沙盒机制
二、用户偏好设置
三、归档
一、沙盒机制
iOS应用沙盒结构分析
1 //获取home目录 2 NSString *homePath = NSHomeDirectory(); 3 NSLog(@"home%@",homePath); 4 5 //获取documents目录 6 //方式1： 7 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 8 NSString *documentsPath = [documents lastObject]; 9 NSLog(@"%@",documentsPath); 10 //方式2：拼接字符串 11 NSString *documentPath2 = [homePath stringByAppendingPathComponent:@"Documents"]; 12 NSLog(@"documenPath2:%@",documentPath2); 13 14 //获取caches缓存目录 15 NSArray *caches = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); 16 NSString *cachesPath = [caches lastObject]; 17 NSLog(@"cachesPath:%@",cachesPath); 18 19 //获取临时目录 20 NSString *tmp = NSTemporaryDirectory(); 21 NSLog(@"tmp:%@",tmp); 22 23 //在documents目录下创建文件 24 NSFileManager *fm = [NSFileManager defaultManager]; 25 NSString *fileName = [documentsPath stringByAppendingPathComponent:@"1.txt"]; 26 NSString *str = @"hello world"; 27 NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding]; 28 29 if ([fm createFileAtPath:fileName contents:data attributes:nil]) { 30 NSLog(@"file create successful"); 31 } 32 33 //读出文件的内容 34 NSError *error = nil; 35 36 NSString *str2 = [NSString stringWithContentsOfFile:fileName encoding:NSUTF8StringEncoding error:&error]; 37 if (!error) { 38 NSLog(@"str2:%@",str2); 39 } 40 else 41 { 42 NSLog(@"%@",error); 43 } 44 //NSBundle对象：图片、xib、storyBoard、plist文件都是放在应用程序包中 45 NSBundle *bundle = [NSBundle mainBundle]; 46 //获取包中文件的路径； 47 NSString *path = [bundle pathForResource:@"array" ofType:@"plist"]; 48 //加载包中的xib文件 49 NSArray *views = [bundle loadNibNamed:@"cell" owner:self options:nil];
二、Preference(用户偏好设置)
很多iOS应?用都?持偏好设置,?如保存?户名、密码、字体?小等设置, iOS提供了?套标准的解决?案来为应用加?偏好设置功能
每个应?都有个NSUserDefaults实例,通过它来存取偏好设置。
1）偏好设置是专门用来保存应用程序的配置信息的, 一般情况不要在偏好设置中保存其他数据。如果利用系统的偏好设置来存储数据, 默认就是存储在Preferences文件夹下面的，偏好设置会将所有的数据都保存到同一个文件中。
2）使用偏好设置对数据进行保存之后, 它保存到系统的时间是不确定的，会在将来某一时间点自动将数据保存到Preferences文件夹下面，如果需要即刻将数据存储，可以使用[defaults synchronize];
3)注意点：所有的信息都写在一个文件中，对比简单的plist可以保存和读取基本的数据类型。
4)步骤：获取NSuserDefaults,保存（读取）数据
代码参考如下：
创建用户偏好设置，保存信息 #import "AppDelegate.h" ...... - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { //创建用户偏好设置对象 NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; [userDefaults setObject:@"admin" forKey:@"userName"]; [userDefaults setObject:@"123456" forKey:@"userPassword"]; [userDefaults setInteger:2 forKey:@"loginTime"]; [userDefaults setObject: [NSDate date] forKey:@"loginDate"]; //同步保存 [userDefaults synchronize]; NSLog(@"%@",NSHomeDirectory()); return YES; } ...... //创建偏好设置，读取信息（注意:NSUserDefaults是单例对象） #import "ViewController.h" ...... - (void)viewDidLoad { [super viewDidLoad]; NSUserDefaults *userDefault = [NSUserDefaults standardUserDefaults]; NSString *userName = [userDefault objectForKey:@"userName"]; NSString *userPassword = [userDefault objectForKey:@"userPassword"]; NSInteger loginTime = [userDefault integerForKey:@"loginTime"]; NSDate *loginDate = [userDefault objectForKey:@"loginDate"]; NSDateFormatter *df = [[NSDateFormatter alloc]init]; NSString *Date = [df stringFromDate:loginDate]; NSLog(@"%@,%@,%ld,%@",userName,userPassword,loginTime,loginDate); } ......
注意:UserDefaults设置数据时,不是立即写入,而是根据时间戳定时地把缓存中的数据写?本地磁盘。所以调?了set方法之后数据有可能还没有写入磁盘应用程序就终止了。出现以上问题,可以通过调?synchornize方法强制写入。
三、NSKeyedArchiver(归档)
1.如果对象是NSString、NSDictionary、NSArray、NSData、NSNumber等类型,可以直接?用NSKeyedArchiver进?行归档和恢复
//创建需要归档的对象数据 NSArray *array = @[@1,@2,@4,@3]; //创建拼接路径 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *path = [documents lastObject]; NSString *archiverPath = [path stringByAppendingPathComponent:@"archiver.arc"]; //执行归档操作 if ([NSKeyedArchiver archiveRootObject:array toFile:archiverPath]) { NSLog(@"归档成功"); } else { NSLog(@"归档失败"); } //打印Home目录 NSLog(@"%@",NSHomeDirectory()); //解归档操作 NSArray *array2 = [NSKeyedUnarchiver unarchiveObjectWithFile:archiverPath]; NSLog(@"%@",array2);
2.不是所有的对象都可以直接用这种方法进行归档,只有遵守了NSCoding协议的对象才可以，NSCoding协议有2个?方法: 实例变量,可以使用encodeObject:forKey:?法归档实例变量
ViewController.m文件代码如下：
#import "ViewController.h" #import "Person.h" ...... [super viewDidLoad]; Person *person = [[Person alloc]init]; person.name = @"zhangsan"; person.age = 22; person.gender = ‘F‘; //拼接保存路径 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *path = [documents lastObject]; NSString *archiverPath = [path stringByAppendingPathComponent:@"archiver.arc"]; //执行归档操作 if ([NSKeyedArchiver archiveRootObject:person toFile:archiverPath]) { NSLog(@"归档成功"); } else { NSLog(@"归档失败"); } NSLog(@"%@",NSHomeDirectory()); //解归档，创建新的对象 Person *person2 = [NSKeyedUnarchiver unarchiveObjectWithFile:archiverPath]; NSLog(@"%@",person2); .....
Person.m代码如下：
#import "Person.h" @implementation Person -(instancetype)initWithName:(NSString *)name andAge:(NSInteger)age andGender:(char)gender { if (self = [super init]) { _name = [name copy]; _age = age; _gender = gender; } return self; } -(NSString *)description { return [NSString stringWithFormat:@"name:%@,age:%ld,gender:%c",_name,_age,_gender]; } -(void)encodeWithCoder:(NSCoder *)aCoder { [aCoder encodeObject:self.name forKey:@"name"]; [aCoder encodeInteger:self.age forKey:@"age"]; [aCoder encodeInteger:self.gender forKey:@"gender"]; } -(id)initWithCoder:(NSCoder *)aDecoder { self.name = [aDecoder decodeObjectForKey:@"name"]; self.age = [aDecoder decodeIntegerForKey:@"age"]; self.gender = [aDecoder decodeIntegerForKey:@"gender"]; return self; } @end
NSKeyedArchiver-归档对象的注意如果?类也遵守了NSCoding协议,请注意:
应该在encodeWithCoder:?法中加上?一句 [super encodeWithCode:encode];
确保继承的实例变量也能被编码,即也能被归档
应该在initWithCoder:?法中加上?一句self = [super initWithCoder:decoder];
确保继承的实例变量也能被解码,即也能被恢复
3.NSData进行多个对象归档
NSString *userName = @"zhangsan"; NSInteger age = 22; NSString *address = @"北京尚学堂"; //创建一个可变数据区，用于保存对象 NSMutableData *data = [[NSMutableData alloc]init]; //拼接路径 NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *path = [documents lastObject]; NSString *archiverPath = [path stringByAppendingPathComponent:@"archiver.arc"]; //创建归档对象，将要归档的对象加入data可变数据区中 NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data]; //归档操作 [archiver encodeObject:userName forKey:@"name"]; [archiver encodeInteger:age forKey:@"age"]; [archiver encodeObject:address forKey:@"address"]; //结束归档 [archiver finishEncoding]; //将data的数据写入到文件中，保存起来。 [data writeToFile:archiverPath atomically:YES]; //创建新的可变数据区 NSMutableData *data2 = [NSMutableData dataWithContentsOfFile:archiverPath]; //解归档操作 NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:data2]; NSString *name = [unarchiver decodeObjectForKey:@"name" ]; NSInteger age2 = [unarchiver decodeIntegerForKey:@"age"]; NSString *address2 = [unarchiver decodeObjectForKey:@"address"]; NSLog(@"name:%@,age:%ld,address:%@",name,age2,address2);
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原文地址：http://www.cnblogs.com/xjf125/p/4848367.html
