iOS开发之沙盒和文件操作

February 24th, 2016

目录

iphone沙箱

沙盒文件说明

iphone沙箱模型的有四个文件夹，分别为：

1、Documents 目录：您应该将所有de应用程序数据文件写入到这个目录下。这个目录用于存储用户数据或其它应该定期备份的信息。

2、AppName.app 目录：这是应用程序的程序包目录，包含应用程序的本身。由于应用程序必须经过签名，所以您在运行时不能对这个目录中的内容进行修改，否则可能会使应用程序无法启动。

3、Library 目录：这个目录下有两个子目录：Caches 和 Preferences
Preferences 目录：包含应用程序的偏好设置文件。您不应该直接创建偏好设置文件，而是应该使用NSUserDefaults类来取得和设置应用程序的偏好.
Caches 目录：用于存放应用程序专用的支持文件，保存应用程序再次启动过程中需要的信息。

4、tmp 目录：这个目录用于存放临时文件，保存应用程序再次启动过程中不需要的信息。

获取沙盒几个目录的方式

// 获取沙盒主目录路径  
NSString *homeDir = NSHomeDirectory();  
// 获取Documents目录路径  
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);  
NSString *docDir = [paths objectAtIndex:0];  
// 获取Caches目录路径  
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);  
NSString *cachesDir = [paths objectAtIndex:0];  
// 获取tmp目录路径  
NSString *tmpDir =  NSTemporaryDirectory();  

// 获取当前程序包中一个图片资源（apple.png）路径  
NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"apple" ofType:@"png"];  
UIImage *appleImage = [[UIImage alloc] initWithContentsOfFile:imagePath];

NSFileManager文件操作封装

NSFileManager:此类主要是对文件进行的操作以及文件信息的获取

获取Documents路径：

- (NSString *)getDocumentsPath
{
    //获取Documents路径
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [paths objectAtIndex:0];
    NSLog(@"path:%@", path);
    return path;
}

创建文件夹

-(void)createDirectory{
    NSString *documentsPath =[self getDocumentsPath];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *iOSDirectory = [documentsPath stringByAppendingPathComponent:@"iOS"];
    BOOL isSuccess = [fileManager createDirectoryAtPath:iOSDirectory withIntermediateDirectories:YES attributes:nil error:nil];
    if (isSuccess) {
        NSLog(@"success");
    } else {
        NSLog(@"fail");
    }
}

创建文件

-(void)createFile{
    NSString *documentsPath =[self getDocumentsPath];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *iOSPath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    BOOL isSuccess = [fileManager createFileAtPath:iOSPath contents:nil attributes:nil];
    if (isSuccess) {
        NSLog(@"success");
    } else {
        NSLog(@"fail");
    }
}

写文件

-(void)writeFile{
    NSString *documentsPath =[self getDocumentsPath];
    NSString *iOSPath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    NSString *content = @"我要写数据啦";
    BOOL isSuccess = [content writeToFile:iOSPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
    if (isSuccess) {
        NSLog(@"write success");
    } else {
        NSLog(@"write fail");
    }
}

读取文件内容

-(void)readFileContent{
    NSString *documentsPath =[self getDocumentsPath];
    NSString *iOSPath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    NSString *content = [NSString stringWithContentsOfFile:iOSPath encoding:NSUTF8StringEncoding error:nil];
    NSLog(@"read success: %@",content);
}

判断文件是否存在

- (BOOL)isSxistAtPath:(NSString *)filePath{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL isExist = [fileManager fileExistsAtPath:filePath];
    return isExist;
}

计算文件大小

- (unsigned long long)fileSizeAtPath:(NSString *)filePath{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL isExist = [fileManager fileExistsAtPath:filePath];
    if (isExist){
        unsigned long long fileSize = [[fileManager attributesOfItemAtPath:filePath error:nil] fileSize];
        return fileSize;
    } else {
        NSLog(@"file is not exist");
        return 0;
    }
}

计算整个文件夹中所有文件大小

- (unsigned long long)folderSizeAtPath:(NSString*)folderPath{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    BOOL isExist = [fileManager fileExistsAtPath:folderPath];
    if (isExist){
        NSEnumerator *childFileEnumerator = [[fileManager subpathsAtPath:folderPath] objectEnumerator];
        unsigned long long folderSize = 0;
        NSString *fileName = @"";
        while ((fileName = [childFileEnumerator nextObject]) != nil){
            NSString* fileAbsolutePath = [folderPath stringByAppendingPathComponent:fileName];
            folderSize += [self fileSizeAtPath:fileAbsolutePath];
        }
        return folderSize / (1024.0 * 1024.0);
    } else {
        NSLog(@"file is not exist");
        return 0;
    }
}

删除文件

-(void)deleteFile{
    NSString *documentsPath =[self getDocumentsPath];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *iOSPath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    BOOL isSuccess = [fileManager removeItemAtPath:iOSPath error:nil];
    if (isSuccess) {
        NSLog(@"delete success");
    }else{
        NSLog(@"delete fail");
    }
}

移动文件

- (void)moveFileName
{
    NSString *documentsPath =[self getDocumentsPath];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *filePath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    NSString *moveToPath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    BOOL isSuccess = [fileManager moveItemAtPath:filePath toPath:moveToPath error:nil];
    if (isSuccess) {
        NSLog(@"rename success");
    }else{
        NSLog(@"rename fail");
    }
}

重命名

- (void)renameFileName
{
    //通过移动该文件对文件重命名
    NSString *documentsPath =[self getDocumentsPath];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *filePath = [documentsPath stringByAppendingPathComponent:@"iOS.txt"];
    NSString *moveToPath = [documentsPath stringByAppendingPathComponent:@"rename.txt"];
    BOOL isSuccess = [fileManager moveItemAtPath:filePath toPath:moveToPath error:nil];
    if (isSuccess) {
        NSLog(@"rename success");
    }else{
        NSLog(@"rename fail");
    }
}

NSFileHandle 文件操作封装

NSFileHandle:此类主要是对文件内容进行读取和写入操作.

NSFileHandle处理文件的步骤：

  1. 打开文件，并获取一个NSFileHandle对象，以便在后面的I/O操作中引用该文件

  2. 对打开的文件执行I/O操作（读取、写入、更新）

  3. 关闭文件

常用处理方法

+ (id)fileHandleForReadingAtPath:(NSString *)path  打开一个文件准备读取     

+ (id)fileHandleForWritingAtPath:(NSString *)path  打开一个文件准备写入   

+ (id)fileHandleForUpdatingAtPath:(NSString *)path  打开一个文件准备更新  

-  (NSData *)availableData; 从设备或通道返回可用的数据            

-  (NSData *)readDataToEndOfFile; 从当前的节点读取到文件的末尾               

-  (NSData *)readDataOfLength:(NSUInteger)length; 从当前节点开始读取指定的长度数据                           

-  (void)writeData:(NSData *)data; 写入数据         

-  (unsigned long long)offsetInFile;  获取当前文件的偏移量            

-  (void)seekToFileOffset:(unsigned long long)offset; 跳到指定文件的偏移量     

-  (unsigned long long)seekToEndOfFile; 跳到文件末尾        

-  (void)truncateFileAtOffset:(unsigned long long)offset; 将文件的长度设为offset字节

-  (void)closeFile;  关闭文件

向文件追加数据

- (void)writeDataToFile:(NSData *)aData{
	NSString *homePath  = NSHomeDirectory( );        
	
	NSString *sourcePath = [homePath stringByAppendingPathConmpone:@"testfile.text"];                                            
	
	NSFileHandle *fielHandle = [NSFileHandle fileHandleForUpdatingAtPath:sourcePath];                                                        
	
	[fileHandle seekToEndOfFile];  将节点跳到文件的末尾          

	[fileHandle writeData:aData]; 追加写入数据       
	
	[fileHandle closeFile];

}

复制文件

- (void)copyFromFile:(NSString *)sourcePath  toOutPath:(NSString *)outPath{
	NSFileHandle *infile, *outfile; //输入文件、输出文件          
	
	NSData *buffer; //读取的缓冲数据                    
	
	NSFileManager *fileManager = [NSFileManager defaultManager];   
	
	NSString *homePath = NSHomeDirectory( );              
	                            
	
	BOOL sucess  = [fileManager createFileAtPath:outPath contents:nil attributes:nil];  
	
	if (!success)          
	
	{                                                      
	
	return N0;                                                                                                   
	
	}                 
	
	infile = [NSFileHandle fileHandleForReadingAtPath:sourcePath]; 创建读取源路径文件
	
	if (infile == nil)                          
	
	{                                          
	
	return NO;                      
	
	}                           
	
	outfile = [NSFileHandle fileHandleForReadingAtPath:outPath]; 创建病打开要输出的文件                                                                                                                
	
	if (outfile == nil)                            
	
	{                                                               
	
	return NO;                                                    
	
	}                                             
	
	[outfile truncateFileAtOffset:0]; 将输出文件的长度设为0         
	
	buffer = [infile readDataToEndOfFile];  读取数据           
	
	[outfile writeData:buffer];  写入输入                        
	
	[infile closeFile];        关闭写入、输入文件               
	
	[outfile closeFile]；
}

向指定文件中读出数据

- (NSData *)readDataFromFile:(NSString *)filepath fromLength:(NSUInteger)length{
	 NSFileHandle *filehandle = [NSFileHandle fileHandleForUpdatingAtPath:filepath];
        
    NSUInteger length = [filehandle availableData].length;
    [filehandle seekToFileOffset:length/2];
    
    NSData *data = [filehandle readDataToEndOfFile];
    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    
    NSLog(@"the data is :%@",str);
    [filehandle closeFile];
}

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hetaodie

Mobile development

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