有没有按特定顺序获取文件夹内容的方法？我想要一个按修改日期排序的文件属性字典（或只是文件名）数组。
现在，我正在这样做：
接下来我必须按日期顺序输出字典，但我想知道是否有更简单的方法？如果没有，是否有代码 sn-p 可以为我执行此操作？
谢谢。
【问题讨论】：
标签： iphone objective-c nsfilemanager
这个怎么样：
// Application documents directory
NSURL *documentsURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
NSArray *directoryContent = [[NSFileManager defaultManager] contentsOfDirectoryAtURL:documentsURL
includingPropertiesForKeys:@[NSURLContentModificationDateKey]
options:NSDirectoryEnumerationSkipsHiddenFiles
error:nil];
NSArray *sortedContent = [directoryContent sortedArrayUsingComparator:
^(NSURL *file1, NSURL *file2)
{
// compare
NSDate *file1Date;
[file1 getResourceValue:&file1Date forKey:NSURLContentModificationDateKey error:nil];
NSDate *file2Date;
[file2 getResourceValue:&file2Date forKey:NSURLContentModificationDateKey error:nil];
// Ascending:
return [file1Date compare: file2Date];
// Descending:
//return [file2Date compare: file1Date];
}];
【讨论】：
更简单...
NSArray* filelist_sorted;
filelist_sorted = [filelist_raw sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSDictionary* first_properties = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:@"%@/%@", path_thumb, obj1] error:nil];
NSDate* first = [first_properties objectForKey:NSFileModificationDate];
NSDictionary* second_properties = [[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithFormat:@"%@/%@", path_thumb, obj2] error:nil];
NSDate* second = [second_properties objectForKey:NSFileModificationDate];
return [second compare:first];
}];
【讨论】：
太慢了
[[NSFileManager defaultManager]
attributesOfItemAtPath:NSFileModificationDate
error:&error];
试试这个代码：
+ (NSDate*) getModificationDateForFileAtPath:(NSString*)path {
struct tm* date; // create a time structure
struct stat attrib; // create a file attribute structure
stat([path UTF8String], &attrib); // get the attributes of afile.txt
date = gmtime(&(attrib.st_mtime)); // Get the last modified time and put it into the time structure
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setSecond: date->tm_sec];
[comps setMinute: date->tm_min];
[comps setHour: date->tm_hour];
[comps setDay: date->tm_mday];
[comps setMonth: date->tm_mon + 1];
[comps setYear: date->tm_year + 1900];
NSCalendar *cal = [NSCalendar currentCalendar];
NSDate *modificationDate = [[cal dateFromComponents:comps] addTimeInterval:[[NSTimeZone systemTimeZone] secondsFromGMT]];
[comps release];
return modificationDate;
}
【讨论】：
代码在 iPhone SDK 中不起作用，充满了编译错误。请找到更新的代码 `
NSInteger lastModifiedSort(id path1, id path2, void* context)
{
int comp = [[path1 objectForKey:@"lastModDate"] compare:
[path2 objectForKey:@"lastModDate"]];
return comp;
}
-(NSArray *)filesByModDate:(NSString*) path{
NSError* error = nil;
NSArray* filesArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:path
error:&error];
if(error == nil)
{
NSMutableArray* filesAndProperties = [NSMutableArray arrayWithCapacity:[filesArray count]];
for(NSString* imgName in filesArray)
{
NSString *imgPath = [NSString stringWithFormat:@"%@/%@",path,imgName];
NSDictionary* properties = [[NSFileManager defaultManager]
attributesOfItemAtPath:imgPath
error:&error];
NSDate* modDate = [properties objectForKey:NSFileModificationDate];
if(error == nil)
{
[filesAndProperties addObject:[NSDictionary dictionaryWithObjectsAndKeys:
imgName, @"path",
modDate, @"lastModDate",
nil]];
}else{
NSLog(@"%@",[error description]);
}
}
NSArray* sortedFiles = [filesAndProperties sortedArrayUsingFunction:&lastModifiedSort context:nil];
NSLog(@"sortedFiles: %@", sortedFiles);
return sortedFiles;
}
else
{
NSLog(@"Encountered error while accessing contents of %@: %@", path, error);
}
return filesArray;
}
`
【讨论】：
以上纳尔的代码为我指明了正确的方向，但我认为上面发布的代码存在一些错误。例如：
filesAndProperties 分配使用NMutableDictonary 而不是NSMutableArray？
NSDictionary* properties = [[NSFileManager defaultManager]
attributesOfItemAtPath:NSFileModificationDate
error:&error];
attributesOfItemAtPath 传递了错误的参数 - 它应该是 attributesOfItemAtPath:path
files 数组进行排序，但您应该对filesAndProperties 进行排序。
我已经实现了相同的功能，并进行了更正，并使用了块并发布在下面：
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsPath = [searchPaths objectAtIndex: 0];
NSError* error = nil;
NSArray* filesArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsPath error:&error];
if(error != nil) {
NSLog(@"Error in reading files: %@", [error localizedDescription]);
return;
}
// sort by creation date
NSMutableArray* filesAndProperties = [NSMutableArray arrayWithCapacity:[filesArray count]];
for(NSString* file in filesArray) {
NSString* filePath = [iMgr.documentsPath stringByAppendingPathComponent:file];
NSDictionary* properties = [[NSFileManager defaultManager]
attributesOfItemAtPath:filePath
error:&error];
NSDate* modDate = [properties objectForKey:NSFileModificationDate];
if(error == nil)
{
[filesAndProperties addObject:[NSDictionary dictionaryWithObjectsAndKeys:
file, @"path",
modDate, @"lastModDate",
nil]];
}
}
// sort using a block
// order inverted as we want latest date first
NSArray* sortedFiles = [filesAndProperties sortedArrayUsingComparator:
^(id path1, id path2)
{
// compare
NSComparisonResult comp = [[path1 objectForKey:@"lastModDate"] compare:
[path2 objectForKey:@"lastModDate"]];
// invert ordering
if (comp == NSOrderedDescending) {
comp = NSOrderedAscending;
}
else if(comp == NSOrderedAscending){
comp = NSOrderedDescending;
}
return comp;
}];
【讨论】：
return [[path2 objectForKey:@"lastModDate"] compare:[path1 objectForKey:@"lastModDate"]];