IOS 初級資料持久化-沙箱機制

標籤：沙箱

什麼是資料持久化?資料的永久儲存

為什麼要坐資料持久化:儲存在記憶體中的資料,程式關閉,記憶體釋放,資料丟失,這種資料是臨時的

資料初九化的本質:資料儲存成檔案,儲存到程式的沙河中

1.沙箱機制

每個應用程式位於檔案系統的嚴格限制部分

每個應用程式只能在為該程式建立的檔案系統中讀取檔案

每個應用程式在IOS系統內都放在了統一的檔案夾目錄下

沙箱的本質就是一個檔案夾,名字是隨機分配的.

2.沙箱路徑的位置

1.通過Finder尋找程式沙箱相對的路徑

通過代碼尋找程式沙箱相對路徑

NSString *DocumentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSLog(@"%@",DocumentPath);

2.沙箱構成

Document                   儲存使用者資料,需要備份的資訊

Library/Caches          儲存快取檔案,程式專用的支援檔案

Library/Preferences          儲存應用程式的喜好設定檔案

.app                           程式包(IOS8時,app不儲存在沙箱中,有單獨的檔案夾儲存所有程式的app包)

tmp                             儲存臨時檔案,比如:下載的zip包,解壓後的再刪除

3.擷取沙箱目錄路徑的方法

NSHomeDirectory-------------------->沙箱主路徑

NSDocumentDirectory--------------->Document檔案夾

NSLibraryDirectory------------------->Library檔案夾

NSCachesDirectory------------------>Caches檔案夾

NSTemporaryDirectory--------------->tem檔案夾

代碼

<span style="font-family:SimHei;font-size:18px;">//1.home主目錄裡面有:Documents,Library,tmp和一個應用程式    NSLog(@"Home:%@",NSHomeDirectory());    //2.DocumentsPath路徑    NSString *DocumentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    NSLog(@"DocumentsPath:%@",DocumentsPath);    //3.Libray    NSString *librayPath = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES)[0];    NSLog(@"%@",librayPath);    //4.temp    NSLog(@"temp:%@",NSTemporaryDirectory());    //5.cachesPath    NSString *cachesPath = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)[0];    NSLog(@"cachesPath:%@",cachesPath);    //6.user    NSString *user = NSUserName();    NSLog(@"user:%@",user);</span>

------------------------------------------------>>>>簡單檔案寫入

<span style="font-family:SimHei;font-size:18px;">//nsstring寫入        //1.寫入的路徑    NSString *DocumentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    NSLog(@"%@",DocumentPath);    //2.拼接檔案路徑    NSString *filePath = [DocumentPath stringByAppendingString:@"/myText.txt"];    //3.準備寫入的內容    NSString *content = @"Hello World";    [content writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];    //4.讀取    NSString *readString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];    NSLog(@"redstring : %@",readString);                //NSArray    //1.擷取documents路徑    //2.拼接檔案路徑    NSString *arrayFile = [DocumentPath stringByAppendingString:@"/array.plist"];    NSLog(@"arrayPath = %@",arrayFile);    //3.準備內容    NSArray * contentArray = @[@"1",@"2",@"3",@"4",@"5",];    //4.寫入    [contentArray writeToFile:arrayFile atomically:YES];    //5.讀取    NSArray *readArray = [NSArray arrayWithContentsOfFile:arrayFile];    NSLog(@"readArray : %@",readArray);        //dictinary    //1.拼接    NSString *dictFile = [DocumentPath stringByAppendingString:@"/dict.plist"];    //2.準備內容    NSDictionary *dictcontent = @{@"1":@"a",@"2":@"b",@"3":@"c"};    NSLog(@"%@",dictFile);    //3.寫入    [dictcontent writeToFile:dictFile atomically:YES];    //4.讀取字典    NSDictionary *readDict = [NSDictionary dictionaryWithContentsOfFile:dictFile];    NSLog(@"dict : %@",readDict);</span>

-------------------------------->>>NSFileManager

NSFileManager,檔案管理,使用detaultManager,建立單利對象

可以建立檔案夾

可以建立,移動,複製,刪除檔案,

可以判斷檔案是否存在

<span style="font-family:SimHei;font-size:18px;"> //NSFileManager    //建立檔案夾    //在Documents中建立一個檔案夾    NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    //在Documents中建立一個檔案夾命名為"個人收藏"    NSString *path = [documentsPath stringByAppendingString:@"/個人收藏"];    //建立檔案管理(單利),並建立檔案夾    [[NSFileManager defaultManager]createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:nil];    NSLog(@"DocumentsPath%@",documentsPath);    //修改檔案夾    NSString *newPath = [documentsPath stringByAppendingString:@"/島國文化"];    [[NSFileManager defaultManager]moveItemAtPath:path toPath:newPath error:nil];    //刪除    [[NSFileManager defaultManager]removeItemAtPath:documentsPath error:nil];    //判斷某個檔案是否存在    //傳回值是BOOL,YES存在,NO不存在    [[NSFileManager defaultManager]fileExistsAtPath:newPath];</span>

--------------------------------------------------->>>>複雜物件寫入檔案(歸檔/反歸檔)

1.什麼是複雜物件

1.在foundation架構內不存在的資料類

2.無法在程式內通過writeToFile類型的方法寫入到檔案內

3.複雜物件至少包含一個執行個體對象

複雜物件無法通過writeToFile:方法進行資料持久化,只能通過將複雜物件轉換為NSData,通過writeToFile進行資料持久化

將複雜的對象轉化為NSData,通過歸檔;將NSData轉換為複雜物件,通過反歸檔

複雜物件寫入檔案要遵循NSCoding協議

有兩個方法,代碼如下:

<span style="font-family:SimHei;font-size:18px;">//進行歸檔時調用(系統調用)-(void)encodeWithCoder:(NSCoder *)aCoder{    //對屬性進行編碼    [aCoder encodeObject:self.name forKey:kName];    [aCoder encodeObject:self.age forKey:kAge];}//進行反歸檔編碼時-(id)initWithCoder:(NSCoder *)aDecoder{    self = [super init];    //反編碼    if (self)    {        self.name = [aDecoder decodeObjectForKey:kName];    }    return self;}</span>

建立一個Person類

歸檔/反歸檔代碼如下:

<span style="font-family:SimHei;font-size:18px;">//歸檔 反歸檔    //建立 Person類執行個體對象    Person *person1 = [[Person alloc] init];    person1.name = @"劉傑";    person1.age = @"39";        Person *person2 = [[Person alloc] init];    person2.name = @"李士傑";    person2.age = @"18";    //歸檔使用的NSData    NSMutableData *Person1Data = [NSMutableData data];    //建立歸檔工具    NSKeyedArchiver * archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:Person1Data];    //進行歸檔    [archiver encodeObject:person1 forKey:kPerson1];    [archiver encodeObject:person2 forKey:kPerson2];    //完成轉換    [archiver finishEncoding];    //找到路徑    NSString *docunment = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    //拼接檔案路徑    NSString *personPath = [docunment stringByAppendingString:@"/劉傑.xxoo"];    //寫入文檔        [Person1Data writeToFile:personPath atomically:YES];    NSLog(@"%@",docunment);        //反歸檔    //通過檔案路徑,擷取data資料    NSData * unData = [NSData dataWithContentsOfFile:personPath];        //反歸檔工具    NSKeyedUnarchiver *unAechiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:unData];        //反歸檔    Person *p1 = [unAechiver decodeObjectForKey:kPerson1];    Person *p2 = [unAechiver decodeObjectForKey:kPerson2];    //結束反歸檔    [unAechiver finishDecoding];        NSLog(@"name:%@",p1.name);    NSLog(@"name :%@",p2.name);</span>

單個歸檔.反歸檔

<span style="font-family:SimHei;font-size:18px;">    //擷取Documents路徑    NSString *DocumentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    //拼接檔案路徑    NSString *filePath = [DocumentsPath stringByAppendingString:@"/PersonArray.plist"];    //執行個體一個對象        Person *p1 = [[Person alloc] init];    p1.name = @"別鬧了";    p1.age = @"1";    //歸檔    [NSKeyedArchiver archiveRootObject:p1 toFile:filePath];    //反歸檔    Person *p2 = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];    NSLog(@"name: %@",p2.name);</span>

多個歸檔/反歸檔

<span style="font-family:SimHei;font-size:18px;"> //擷取Documents路徑    NSString *DocumentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];    //拼接檔案路徑    NSString *filePath = [DocumentsPath stringByAppendingString:@"/PersonArray.plist"];    //執行個體一個對象    Person *pn1 = [[Person alloc] init];    pn1.name = @"TOM";    pn1.age = @"12";    Person *pn2 = [[Person alloc] init];    pn2.name = @"KIM";    pn2.age = @"18";        NSArray *array = @[pn1,pn2];     //歸檔    [NSKeyedArchiver archiveRootObject:array toFile:filePath];    //反歸檔    NSArray *a = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];    NSLog(@"%@,%@",[a[0] name],[a[1] name]);</span>

沙箱機制:

簡單對象寫入檔案,只能是NSString,NSArray,NSDictionary,NSData

複雜的對象寫入檔案,遵守NSCoding協議,實現代理方法

IOS 初級資料持久化-沙箱機制