iOS進階——沙盒及沙盒路徑、簡單文件的寫入

       iOS每個應用程序都有獨立的空間作爲其運行存儲的地方，不同應用之間不允許互相訪問其空間，在iOS8.0之後，逐步開放了部分權限。

一、獲取程序沙盒主路徑的方法

//沙盒的主路徑
    NSString* homeStrPath = NSHomeDirectory();
    NSLog(@"home--%@",homeStrPath);

 //通過search函數得到doctoments文件的路徑
    /**
     *  Description
     *
     *  @param NSDocumentDirectory 所搜尋的文件夾得主路徑
     *  @param NSUserDomainMask    搜索範圍，此參數是規定搜素區域爲沙盒下的
     *  @param YES                 是否展開，如果是NO的話，是一個~，yes則是完整的路徑
     *
     *  @return 是一個路徑數組的詳細信息
     */
    NSArray *documentArr = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, NO);
    NSString *tem=[documentArr objectAtIndex:0];
    NSLog(@"searchDocuments -- %@",tem);

二、簡單對象的讀寫操作

iOS中提供的4種類型可以直接進行文件的存取：

NSString（字符串）；

NSArray （數組）；

NSDictionary（字典）；

NSdata （數據）；

（以上包括其子類型）。

數組、字典一般寫入爲plist後綴的文件，字符串爲text文件，而數據類型的文件寫入時，不需要加後綴名保存。

三、文件管理器與文件對接器

文件管理器：

//創建文件管理器
    NSFileManager *fileManager = [NSFileManager defaultManager];
    
    BOOL isCreate = [fileManager createDirectoryAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"test"]withIntermediateDirectories:YES attributes:nil error:nil];
    if (isCreate) {
        NSLog(@"goodMan,successful--%@",[SandBoxPaths documentsPath]);
    }else{
        NSLog(@"default");
    }
    BOOL isMoved = [fileManager moveItemAtPath:[SandBoxPaths documentsPath] toPath:[[SandBoxPaths cachesPath] stringByAppendingPathComponent:@"test"] error:nil];
    if (isMoved) {
        NSLog(@"成功");
    }

// 複製文件
        BOOL isCopy = [fileManager copyItemAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"text.txt"]toPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"test/text.txt"] error:nil];
        if (isCopy) {
            NSLog(@"複製成功");
        }else{
            NSLog(@"複製失敗");
        }
    //判斷文件是否相等
    BOOL isEaqul = [fileManager contentsEqualAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"text.txt"] andPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"text.txt"]];
    if (isEaqul) {
        NSLog(@"一致");
    }else{
        NSLog(@"不一致");
    }

    //刪除文件
    [fileManager removeItemAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"text.txt"] error:nil];
    BOOL isExists = [fileManager fileExistsAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"text.txt"]];
    if (isExists) {
        NSLog(@"存在");
    }else{
        NSLog(@"不存在");
    }

文件對接器：

//    創建一個準備讀取的handle對象
    NSFileHandle *readHandle = [NSFileHandle fileHandleForReadingAtPath:[[SandBoxPaths documentsPath]stringByAppendingPathComponent:@"handle.txt"]];
//    完整讀取文件
    NSData *endData = [readHandle readDataToEndOfFile];
    NSString *string = [[NSString alloc]initWithData:endData encoding:NSUTF8StringEncoding];
    NSLog(@"%@",string);
    
    NSData *lenthData = [readHandle readDataOfLength:8];
    NSString *string7 = [[NSString alloc]initWithData:lenthData encoding:NSUTF8StringEncoding];
    NSLog(@"特定長度%@",string7);
    
    NSInteger lenth = [[readHandle availableData] length];
    NSLog(@"%ld",lenth);
//    創建一個可以寫入的文件對象
    NSFileHandle *writeHandle = [NSFileHandle fileHandleForWritingAtPath:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"handle.txt"]];
    //改變文件的偏移量
    [writeHandle seekToFileOffset:3];
    [writeHandle writeData:[@"5678" dataUsingEncoding:NSUTF8StringEncoding]];
    //從指定路徑下讀取文件
    NSString* result = [NSString stringWithContentsOfFile:[[SandBoxPaths documentsPath] stringByAppendingPathComponent:@"handle.txt"] encoding:NSUTF8StringEncoding error:nil];
    NSLog(@"%@",result);

四、複雜對象的讀寫

<span style="font-size:14px;">//歸檔方法
-(void)archiver{
    //創建需要歸檔的對象
    UserInfoModel *boy = [[UserInfoModel alloc]init];
    boy.name = @"sb";
    boy.gender = @"ooo";
    boy.age = @"16";
    boy.phoneNum = @"11111111111";
    boy.headImage = nil;
    //創建一個可變的data對象，用來存儲複雜兌現
    NSMutableData *data = [NSMutableData data];//用來接收轉換好之後的複雜對對象的容器
    //歸檔
    NSKeyedArchiver* archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];
    [archiver encodeObject:boy forKey:@"boy"];
    //歸檔結束，只有調用了此方法，纔會存儲爲data類型
    [archiver finishEncoding];
    //將歸檔結束後的數據進行持久化
    //構造存儲路徑
    //存到cache裏
    
    NSArray *caches = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *cachesPath = [[caches objectAtIndex:0] stringByAppendingPathComponent:@"data"];
    
    //存儲數據
    [data writeToFile:cachesPath atomically:YES];
    
}</span>

<span style="font-size:14px;">//反歸檔,將歸檔好的NSData類型轉化爲複雜對象
-(void)enarchiver{
    NSArray *caches = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *cachesPath = [[caches objectAtIndex:0]stringByAppendingPathComponent:@"data"];
    
    NSData *data = [NSData dataWithContentsOfFile:cachesPath];
    
    //反歸檔工具
    NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:data];
    UserInfoModel *boy = [unArchiver decodeObjectForKey:@"boy"];
    [unArchiver finishDecoding];
    NSLog(@"name -- %@",boy.name);
}</span>

//歸檔遵循的協議

@interface UserInfoModel : NSObject<NSCoding>

//實現協議的代理方法，在這裏是對屬性的編碼

//寫此方法防止奔潰因字典的鍵值不匹配問題
-(void)setValue:(id)value forUndefinedKey:(NSString *)key{
    
}

//歸檔的協議方法，實際上是對當前類對象所有的屬性進行歸檔,協議方法在我們歸檔的時候會自動調用
-(void)encodeWithCoder:(NSCoder *)aCoder{
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeObject:self.age forKey:@"age"];
    [aCoder encodeObject:self.gender forKey:@"gender"];
    [aCoder encodeObject:self.phoneNum forKey:@"phoneNum"];
    [aCoder encodeObject:self.headImage forKey:@"headImage"];
    NSLog(@"歸檔的方法已經調用");
}

-(instancetype)initWithCoder:(NSCoder *)aDecoder{
    self = [super init];
    if (self) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.age = [aDecoder decodeObjectForKey:@"age"];
        self.gender = [aDecoder decodeObjectForKey:@"gender"];
        self.phoneNum = [aDecoder decodeObjectForKey:@"phoneNum"];
        self.headImage = [aDecoder decodeObjectForKey:@"headimage"];
    }
    NSLog(@"解檔調用");
    
    return self;
}