大纲
NSFileHandle 此类主要是对文件内容进行读取和写入操作
NSFileManager 此类主要是对文件进行的操作以及文件信息的获取
##常用处理方法
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| /*从设备或通道返回可用的数据*/
@property (readonly, copy) NSData *availableData;
//打开一个文件准备读取
+ (nullable instancetype)fileHandleForReadingAtPath:(NSString *)path;
//打开一个文件准备写入
+ (nullable instancetype)fileHandleForWritingAtPath:(NSString *)path;
//打开一个文件准备更新
+ (nullable instancetype)fileHandleForUpdatingAtPath:(NSString *)path;
//从当前的节点读取到文件的末尾
- (nullable NSData *)readDataToEndOfFileAndReturnError:(out NSError **)error;
//从当前节点开始读取指定的长度数据
- (nullable NSData *)readDataUpToLength:(NSUInteger)length error:(out NSError **)error;
//写入数据
- (BOOL)writeData:(NSData *)data error:(out NSError **)error;
//获取当前文件的偏移量
- (BOOL)getOffset:(out unsigned long long *)offsetInFile error:(out NSError **)error;
//跳到指定文件的偏移量
- (BOOL)seekToOffset:(unsigned long long)offset error:(out NSError **)error;
//跳到文件末尾
- (BOOL)seekToEndReturningOffset:(out unsigned long long *_Nullable)offsetInFile error:(out NSError **)error;
//将文件的长度设为offset字节
- (BOOL)truncateAtOffset:(unsigned long long)offset error:(out NSError **)error;
//关闭文件
- (BOOL)closeAndReturnError:(out NSError **)error;
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##向文件追加数据
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| 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];
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##定位数据
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| 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
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| // 输入文件、输出文件
NSFileHandle *infile, *outfile;NSData *buffer;
//读取的缓冲数据
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *homePath = NSHomeDirectory( );
// 源文件路径
NSString *sourcePath = [homePath stringByAppendingPathComponent:@"testfile.txt"];
//输出文件路径
NSString *outPath = [homePath stringByAppendingPathComponent:@"outfile.txt"];
BOOL sucess = [fileManager createFileAtPath:outPath contents:nil attributes:nil];
if (!success){
return N0;
}
//创建读取源路径文件
infile = [NSFileHandle fileHandleForReadingAtPath:sourcePath];
if (infile == nil){
return NO;
}
//创建病打开要输出的文件
outfile = [NSFileHandle fileHandleForReadingAtPath:outPath];
if (outfile == nil){
return NO;
}
//将输出文件的长度设为0
[outfile truncateFileAtOffset:0];
//读取数据
buffer = [infile readDataToEndOfFile];
// 写入输入
[outfile writeData:buffer];
//关闭写入、输入文件
[infile closeFile];
[outfile closeFile]；
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