[英]Sorting NSArray of Custom Objects by property - DBMetadata - Dropbox
我找不到为什么对DBMetadata (NSObject)
NSArray
排序不起作用的原因。 这是我的代码。 怎么了? 我什至尝试添加一个类别来添加compare:
但是它不起作用。
- (void)restClient:(DBRestClient *)client loadedMetadata:(DBMetadata *)metadata {
if (metadata.isDirectory) {
NSLog(@"Folder '%@' contains:", metadata.path);
for (DBMetadata *file in metadata.contents) {
NSLog(@"\t%@ is directory? %d", file.filename, file.isDirectory);
if (file.isDirectory) {
[self.availableBackups addObject:file];
DLog(@"llastModifiedDate %@", file.lastModifiedDate);
}
}
}
// NSLog(@"before sorting: %@", self.availableBackups); //lastModifiedDate //filename
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:@"lastModifiedDate" ascending:YES selector:@selector(compare:)];
[self.availableBackups sortedArrayUsingDescriptors:[NSArray arrayWithObjects:descriptor,nil]];
// NSLog(@"after sorting: %@", self.availableBackups);
}
self.availableBackups
是NSMutableArray
@property (nonatomic, retain) NSMutableArray *availableBackups;
注释NSLog
仅打印obj的地址,排序后无论YES
或NO
ascending:
,您都可以看到address的输出仍然相同ascending:
输出
2013-01-31 17:20:12.423 Dropbox[7366:c07] before sorting: (
"<DBMetadata: 0x6bbf010>",
"<DBMetadata: 0x6bbfb50>",
"<DBMetadata: 0x6bc1660>",
"<DBMetadata: 0x6bc17b0>",
"<DBMetadata: 0x6bc14f0>",
"<DBMetadata: 0x6bc0dd0>",
"<DBMetadata: 0x6bc1de0>"
)
2013-01-31 17:20:12.424 Dropbox[7366:c07] after sorting: (
"<DBMetadata: 0x6bbf010>",
"<DBMetadata: 0x6bbfb50>",
"<DBMetadata: 0x6bc1660>",
"<DBMetadata: 0x6bc17b0>",
"<DBMetadata: 0x6bc14f0>",
"<DBMetadata: 0x6bc0dd0>",
"<DBMetadata: 0x6bc1de0>"
)
升序NO
Last Modified file at 0: 2013-01-30 08:00:22 +0000
Last Modified file at 1: 2013-01-30 08:02:54 +0000
Last Modified file at 2: 2013-01-31 09:08:26 +0000
Last Modified file at 3: 2013-01-31 09:14:55 +0000
Last Modified file at 4: 2013-01-31 09:14:08 +0000
Last Modified file at 5: 2013-01-31 09:16:43 +0000
Last Modified file at 6: 2013-01-31 10:36:13 +0000
sortedArrayUsingDescriptors:
返回一个数组,它不会修改您要对其应用的数组。 如果需要使用NSArray
,请尝试:
self.availableBackups = [self.availableBackups sortedArrayUsingDescriptors:[NSArray arrayWithObjects:descriptor,nil]];
如果可以使用NSMutableArray
,则可以使用:
[self.availableBackups sortUsingDescriptors:[NSArray arrayWithObjects:descriptor,nil]];
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