IOS开发-文件管理（二）

五、Plist文件

String方式添加

NSString *path = [NSHomeDirectory( ) stringByAppendingPathComponent:@"Array.plist"];

NSString *content = @"abcd";

[contect writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:nil];

Array方式添加

NSString *path = [NSHomeDirectory( ) stringByAppendingPathComponent:@"Array.plist"];

[NSArray *array = [[NSArray alloc] initWithObjects:@"123", @"798"，@"000",nil]; [array writeToFile:path atomically:YES];

Dictionary方式添加

NSString *path = [NSHomeDirectory( ) stringByAppendingPathComponent:@"Dic.plist"];

NSDictionary *dic = [NSDictionary alloc] initWithObjects:@"first",@"second",@"third"forKeys:@"123",@"456",@"798"]; [dic writeToFile:path atomically:YES];

数组、字典只能将BOOL、NSNumber、NSString、NSData、NSDate、NSArray、NSDictionary写入属性列表plist文件

六、读取文件类和常用方法

NSFileHandle类主要对文件内容进行读取和写入操作

NSFileManager类主要对文件的操作（删除、修改、移动、复制等等）

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

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

NSString *str = @"追加的数据"

NSData* stringData = [str dataUsingEncoding:NSUTF8StringEncoding];

[fileHandle writeData:stringData]; 追加写入数据

[fileHandle closeFile];

定位数据

NSFileManager *fm = [NSFileManager defaultManager];

NSString *content = @"abcdef";

[fm createFileAtPath:path contents:[content dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];

NSFileHandle *fileHandle = [NSFileHandle fileHandleForReadingAtPath:path];

NSUInteger length = [fileHandle availabelData] length]; 获取数据长度

[fileHandle seekToFileOffset;length/2]; 偏移量文件的一半

NSData *data = [fileHandle readDataToEndOfFile];

[fileHandle closeFile];

复制文件

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( );

NSString *sourcePath = [homePath stringByAppendingPathComponent:@"testfile.txt"]; 源文件路径

NSString *outPath = [homePath stringByAppendingPathComponent:@"outfile.txt"]; 输出文件路径

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]；

本文转自：http://seven-sally.lofter.com/post/19d861_5619fa