ObjectiveC 文件操作一
1，引用和使用文件
NSFileManager 是一个单例对象，在mac应用中可以获取任何地址，在IOS中获取的是相对应的应用程序的地址。可以使用 defaultManager 来得到当前应用程序地址，例如。
NSFileManager *fileManager = [NSFileManager defaultManager];
模拟器目录 /Users/username/Library/Application Support/iPhone Simulator/
一旦有了参考，你便可以得到相应目录，例如你想得到currentDirectoryPath
目录。
NSString *currentDirectoryPath = [fileManager currentDirectoryPath];
想切换目录，用changeCurrentDirectoryPath，如
[fileManager changeCurrentDirectoryPath:@"/Users/Shared”];
代码例子。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *currentDirectoryPath = [fileManager currentDirectoryPath];
NSLog(@"currentDirectoryPath = %@---", currentDirectoryPath);
[fileManager changeCurrentDirectoryPath:@"/Users/Shared"];
currentDirectoryPath = [fileManager currentDirectoryPath];
NSLog(@"currentDirectoryPath = %@+++", currentDirectoryPath);
2，mac目录引用
使用NSSearchPathForDirectoriesInDomains
例如
NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
NSLog(@"%@++", bundlePath);
打印的值大概是
/Users/guanliyang/Library/Developer/Xcode/DerivedData/filePath-dgfhcnomuvxhzpepzbrxbrfkhkkz/Build/Products/Debug++
如果想得到文档目录
NSString *directoryPathName = [NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory,NSAllDomainsMask, YES) lastObject];
更多参数请参考原著objective－C recipes。
3，获取IOS引用目录
NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
NSLog(@"%@", bundlePath);
这个得到的是你IOS应用的主目录，/Users/guanliyang/Library/Application Support/iPhone Simulator/7.1/Applications/1A888392-101B-40B1-A47A-195C19DBC18E/aa.app
如果你想得到模拟器的文档目录，你可以这样做
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSLog(@"%@", documentsDirectory);
还有其他几个选项，IOS模拟器默认生成的几个目录
NSDocumentDirectory Location for user-generated content (read-write, backed up) The
NSLibraryDirectory app’s library directory (read-write, backed up)
NSCachesDirectory A directory for cached files (read-write, not backed up)
默认只生成这三个目录。
4,获取文件属性。
先指定文件
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePathName = @"/Users/Shared/textfile.txt”;
声明error
NSError *error = nil;
给定文件路径，试着读取文件并查看是否有错。
NSDictionary *fileAttributes = [fileManager attributesOfItemAtPath:filePathName error:&error];
如果没有错误，获取文件相关信息。
if(!error){
NSDate *dateFileCreated = [fileAttributes valueForKey:NSFileCreationDate];
NSString *fileType = [fileAttributes valueForKey:NSFileType];
}
还有很多相关信息可打印，比如大小，所属用户，文件个数等等....
5,获取文件子目录和目录中的目录。
先得到文件列表
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *sharedDirectory = @"/Users/Shared”;
NSError *error = nil;
NSArray *listOfFiles = [fileManager contentsOfDirectoryAtPath:sharedDirectory
error:&error];
递归目录，可以使用subpathsOfDirectoryAtPath:error
例如
NSArray *listOfSubPaths = [fileManager subpathsOfDirectoryAtPath:sharedDirectory
error:&error];
例子代码
int main(int argc, const char * argv[])
{
@autoreleasepool {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *sharedDirectory = @"/Users/Shared";
NSError *error = nil;
NSArray *listOfFiles = [fileManager contentsOfDirectoryAtPath:sharedDirectory
error:&error];
if(!error)
NSLog(@"Contents of shared directory: %@", listOfFiles);
NSArray *listOfSubPaths = [fileManager subpathsOfDirectoryAtPath:sharedDirectory
error:&error];
if(!error)
NSLog(@"Sub Paths of shared directory”: %@", listOfSubPaths);
}
return 0;
}
6，管理目录
用代码操作目录。
使用NSFileManager，
createDirectoryAtPath:withIntermediateDirectories:attributes:error:可以创建目录，
moveItemAtPath:toPath:error: 可以移动目录，
removeItemAtPath:error:删除目录，
copyItemAtPath:toPath:error:拷贝目录
具体代码
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *sharedDirectory = @"/Users/Shared/NewDirectory1/NewSubDirectory1";
NSError *error = nil;
创建
BOOL directoryCreated = [fileManager createDirectoryAtPath:newDirectory
withIntermediateDirectories:YES
attributes:nil
error:&error];
该函数返回布尔值，提示是否创建成功。
同理，移动文件。
NSString *directoryMovedTo = @"/Users/Shared/NewSubDirectory1";
BOOL directoryMoved = [fileManager moveItemAtPath:newDirectory
toPath:directoryMovedTo
error:&error];
删除目录
NSString *directoryToRemove = @"/Users/Shared/NewDirectory1";
BOOL directoryRemoved =[fileManager removeItemAtPath:directoryToRemove
error:&error];
复制目录。
NSString *directoryToCopy = @"/Users/Shared/NewSubDirectory1";
NSString *directoryToCopyTo = @"/Users/Shared/CopiedDirectory";
BOOL directoryCopied =[fileManager copyItemAtPath:directoryToCopy
toPath:directoryToCopyTo
error:&error];
具体代码例子。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *newDirectory =@"/Users/Shared/NewDirectory1/NewSubDirectory1";
NSError *error = nil;
BOOL directoryCreated = [fileManager createDirectoryAtPath:newDirectory
withIntermediateDirectories:YES
attributes:nil
error:&error];
if(!error)
NSLog(@"directoryCreated = %i with no error", directoryCreated);
else
NSLog(@"directoryCreated = %i with error %@", directoryCreated, error);
NSString *directoryMovedTo = @"/Users/Shared/NewSubDirectory1";
BOOL directoryMoved = [fileManager moveItemAtPath:newDirectory
toPath:directoryMovedTo
error:&error];
if(!error)
NSLog(@"directoryMoved = %i with no error", directoryMoved);
else
NSLog(@"directoryMoved = %i with error %@", directoryMoved, error);
NSString *directoryToRemove = @"/Users/Shared/NewDirectory1";
BOOL directoryRemoved =[fileManager removeItemAtPath:directoryToRemove
error:&error];
if(!error)
NSLog(@"directoryRemoved = %i with no error", directoryRemoved);
else
NSLog(@"directoryRemoved = %i with error %@", directoryRemoved, error);
NSString *directoryToCopy = @"/Users/Shared/NewSubDirectory1";
NSString *directoryToCopyTo = @"/Users/Shared/CopiedDirectory";
BOOL directoryCopied =[fileManager copyItemAtPath:directoryToCopy
toPath:directoryToCopyTo
error:&error];
if(!error)
NSLog(@"directoryCopied = %i with no error", directoryCopied);
else
NSLog(@"directoryCopied = %i with error %@", directoryCopied, error);
7，管理文件。
添加，移动，复制，删除文件。
代码例子，图片不能访问可新找一图片地址。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *url = [NSURL URLWithString:@"http://img5.imgtn.bdimg.com/it/u=3163907393,1865504758&fm=23&gp=0.jpg”];
用NSData为图片对象，
NSData *dataObject = [NSData dataWithContentsOfURL:url];
创建图片
NSString *newFile = @"/Users/Shared/apples-oranges.jpg";
BOOL fileCreated = [fileManager createFileAtPath:newFile
contents:dataObject
attributes:nil];
移动图片
NSError *error = nil;
NSString *fileMovedTo = @"/Users/Shared/apples-oranges-moved.jpg";
BOOL fileMoved = [fileManager moveItemAtPath:newFile
toPath:fileMovedTo
error:&error];
删除图片
NSString *fileToRemove = @"/Users/Shared/apples-oranges-moved.jpg";
BOOL fileRemoved =[fileManager removeItemAtPath:fileToRemove
error:&error];
复制图片
NSString *fileToCopy = @"/Users/Shared/apples-oranges-moved.jpg";
NSString *copiedFileName = @"/Users/Shared/apples-oranges-backup-copy.jpg";
BOOL fileCopied = [fileManager copyItemAtPath:fileToCopy
toPath:copiedFileName
error:&error];
具体代码例子。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *url = [NSURL URLWithString:@"http://www.baidu.com/img/baidu_sylogo1.gif"];
NSData *dataObject = [NSData dataWithContentsOfURL:url];
NSString *newFile = @"/Users/Shared/apples-oranges.jpg";
BOOL fileCreated = [fileManager createFileAtPath:newFile
contents:dataObject
attributes:nil];
NSLog(@"fileCreated = %i with no error", fileCreated);
NSError *error = nil;
NSString *fileMovedTo = @"/Users/Shared/apples-oranges-moved.jpg";
BOOL fileMoved = [fileManager moveItemAtPath:newFile
toPath:fileMovedTo
error:&error];
if(!error)
NSLog(@"fileMoved = %i with no error", fileMoved);
else
NSLog(@"fileMoved = %i with error %@", fileMoved, error);
NSString *fileToCopy = @"/Users/Shared/apples-oranges-moved.jpg";
NSString *copiedFileName = @"/Users/Shared/apples-oranges-backup-copy.jpg";
BOOL fileCopied = [fileManager copyItemAtPath:fileToCopy
toPath:copiedFileName
error:&error];
if(!error)
NSLog(@"fileCopied = %i with no error", fileCopied);
else
NSLog(@"fileCopied = %i with error %@", fileCopied, error);
NSString *fileToRemove = @"/Users/Shared/apples-oranges-moved.jpg";
BOOL fileRemoved =[fileManager removeItemAtPath:fileToRemove
error:&error];
if(!error)
NSLog(@"fileRemoved = %i with no error", fileRemoved);
else
NSLog(@"fileRemoved = %i with error %@", fileRemoved, error);
可以更改容易查看目录做具体测试。
8，检查文件状态。
常用方法。
fileExistsAtPath:
isReadableFileAtPath:
isWritableFileAtPath:
isExecutableFileAtPath: isDeletableFileAtPath:.
检查文件是否存在。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePathName = @"/Users/Shared/textfile.txt”;
BOOL fileExists = [fileManager fileExistsAtPath:filePathName];
文件是否可读
BOOL fileIsReadable = [fileManager isReadableFileAtPath:filePathName];
是否可写
BOOL fileIsWriteable = [fileManager isWritableFileAtPath:filePathName];
最后，文件是否可删除。
BOOL fileIsDeleteable = [fileManager isDeletableFileAtPath:filePathName];
具体代码例子。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePathName = @"/Users/Shared/textfile.txt";
BOOL fileExists = [fileManager fileExistsAtPath:filePathName];
if(fileExists)
NSLog(@"%@ exists", filePathName);
else
NSLog(@"%@ doesn't exist", filePathName);
BOOL fileIsReadable = [fileManager isReadableFileAtPath:filePathName];
if(fileIsReadable)
NSLog(@"%@ is readable", filePathName);
else
NSLog(@"%@ isn't readable", filePathName);
BOOL fileIsWriteable = [fileManager isWritableFileAtPath:filePathName];
if(fileIsWriteable)
NSLog(@"%@ is writable", filePathName);
else
NSLog(@"%@ isn't writable", filePathName);
BOOL fileIsExecutable = [fileManager isExecutableFileAtPath:filePathName];
if(fileIsExecutable)
NSLog(@"%@ is an executable", filePathName);
else
NSLog(@"%@ isn't an executable", filePathName);
BOOL fileIsDeleteable = [fileManager isDeletableFileAtPath:filePathName];
if(fileIsDeleteable)
NSLog(@"%@ is deletable", filePathName);
else
NSLog(@"%@ isn't an deletable", filePathName);
没文件可以自己touch创建一个。
9，更改文件属性。
文件管理对象，文件，错误对象。
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePathName = @"/Users/Shared/textfile.txt";
NSError *error = nil;
建立一个字典数组以便获取文件属性列表。
NSMutableDictionary *attributes = [[NSMutableDictionary alloc] init];
[attributes setObject:[NSDate date] forKey:NSFileModificationDate];
我们只改一下文件的修改日期
BOOL attributeChanged = [fileManager setAttributes:attributes
ofItemAtPath:filePathName
error:&error];
具体代码
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePathName = @"/Users/Shared/textfile.txt";
NSError *error = nil;
//Get the file attributes so you can compare later on:
NSDictionary *fileAttributes = [fileManager attributesOfItemAtPath:filePathName
error:&error];
if(!error)
NSLog(@"%@ file attributes (before): %@",filePathName, fileAttributes);
NSMutableDictionary *attributes = [[NSMutableDictionary alloc] init];
[attributes setObject:[NSDate date] forKey:NSFileModificationDate];
BOOL attributeChanged = [fileManager setAttributes:attributes
ofItemAtPath:filePathName
error:&error];
if(error)
NSLog(@"There was an error: %@", error);
else{
NSLog(@"attributeChanged = %i", attributeChanged);
//Get the file attributes to see the change:
NSDictionary *fileAttributes = [fileManager attributesOfItemAtPath:filePathName
error:&error];
if(!error)
NSLog(@"%@ file attributes (after): %@",filePathName, fileAttributes);