NSFileManager使用

NSFileManager代表文件管理器，主要对文件和目录的操作(删除、修改、移动、复制等等)。如果程序需要读取文件内容，则可通过NSHandle进行处理；如果需要读取网络资源，则可通过NSURL进行处理，如果只是读取项目内部资源，则用NSBundle进行处理。

确定文件是否存在

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"file.txt"];
BOOL fileExists = [fileManager fileExistsAtPath:filePath];

列出目录里面的所有文件

NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *bundleURL = [[NSBundle mainBundle] bundleURL];
NSArray *contents = [fileManager contentsOfDirectoryAtURL:bundleURL includingPropertiesForKeys:@[] options:NSDirectoryEnumerationSkipsHiddenFiles error:nil];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"pathExtension == 'png'"];
for (NSURL *fileURL in [contents filteredArrayUsingPredicate:predicate]) {
    NSLog(@"项目内部枚举本地图片 = %@",fileURL);
}

在目录中递归地遍历文件

NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *bundleURL = [[NSBundle mainBundle] bundleURL];

NSDirectoryEnumerator *enumerator = [fileManager enumeratorAtURL:bundleURL includingPropertiesForKeys:@[NSURLNameKey,NSURLIsDirectoryKey] options:NSDirectoryEnumerationSkipsHiddenFiles errorHandler:^BOOL(NSURL * _Nonnull url, NSError * _Nonnull error) {
    if (error) {
        NSLog(@"[Error] %@ (%@)", error, url);
        return NO;
    } else {
        return YES;
    }
}];

NSMutableArray *mutableFileURLs = [NSMutableArray array];
for (NSURL *fileURL in enumerator) {
    NSString *filename;
    [fileURL getResourceValue:&filename forKey:NSURLNameKey error:nil];
    
    NSNumber *isDirectory;
    [fileURL getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:nil];
    
    // Skip directories with '_' prefix, for example
    if ([filename hasPrefix:@"_"] && [isDirectory boolValue]) {
        [enumerator skipDescendants];
        continue;
    }
    
    if (![isDirectory boolValue]) {
        [mutableFileURLs addObject:fileURL];
    }
}

创建一个目录

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *imagesPath = [documentsPath stringByAppendingPathComponent:@"images"];
if (![fileManager fileExistsAtPath:imagesPath]) {
    [fileManager createDirectoryAtPath:imagesPath withIntermediateDirectories:NO attributes:nil error:nil];
}

删除一个目录

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"image.png"];
NSError *error = nil;
if (![fileManager removeItemAtPath:filePath error:&error]) {
    NSLog(@"[Error] %@ (%@)", error, filePath);
}

删除文件的创建日期

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"Document.pages"];

NSDate *creationDate = nil;
if ([fileManager fileExistsAtPath:filePath]) {
    NSDictionary *attributes = [fileManager attributesOfItemAtPath:filePath error:nil];
    creationDate = attributes[NSFileCreationDate];
}

通过NSFileManager的 -attributesOfItemAtPath:error: 和其它方法可以访问很多文件的属性