[英]How do I create an Objective-C NSDictionary of NSArrays without reusing the same NSArray?
[英]how to sort an NSArray of nested NSArrays by array count?
我有一個包含嵌套 NSArray 的 NSArray。 我正在尋找一種方法來根據嵌套 arrays 的 object 計數按升序對父數組進行排序。 所以如果[array1 count]
是 4, [array2 count]
是 2 而[array3 count]
是 9,我會得到:array2,array1,array3...
有幾種解決方案,其中之一是:
NSSortDescriptor *sd = [NSSortDescriptor sortDescriptorWithKey:@"@count"
ascending:YES];
NSArray *sds = [NSArray arrayWithObject:sd];
NSArray *sortedArray = [array sortedArrayUsingDescriptors:sds];
static NSInteger MONSortObjectsAscendingByCount(id lhs, id rhs, void* ignored) {
/* error checking omitted */
const NSUInteger lhsCount = [lhs count];
const NSUInteger rhsCount = [rhs count];
if (lhsCount < rhsCount) {
return NSOrderedAscending;
}
else if (lhsCount > rhsCount) {
return NSOrderedDescending;
}
else {
return NSOrderedSame;
}
}
/* use if mutable, and you wnat it sorted in place */
- (void)sortUsingFunction:(NSInteger (*)(id, id, void *))compare context:(void *)context;
/* else use */
- (NSArray *)sortedArrayUsingFunction:(NSInteger (*)(id, id, void *))compare context:(void *)context;
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