问题
Lets suppose I have an array like this
NSArray* arr = @[@"1",@"4",@"2",@"8",@"11",@"10",@"14",@"9"]; //note: strings containing numbers
and I want to sort them like this: [1,2,4,8,9,10,11,14]
but if I use
[arr sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
I get [1,10,11,14,2,4,8,9]... and if I use:
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"length" ascending:YES];
NSArray *sortDescriptors = @[sortDescriptor];
[arr sortedArrayUsingDescriptors:sortDescriptors];
I get something like this: [1,4,2,8,9,11,10,14]
How can I combine both predicates? or is any other easier way to solve this? note: The output of this array is merely for debug purposes, I dont care if the result turns the array into integers as long as I can print in console with NSLog thanks
回答1:
Try using blocks
[arr sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
if ([obj1 intValue] == [obj2 intValue])
return NSOrderedSame;
else if ([obj1 intValue] < [obj2 intValue])
return NSOrderedAscending;
else
return NSOrderedDescending;
}];
回答2:
The problem is that you're trying to use both string comparison and -length to cobble together what you really want, which is numeric comparison. But sort descriptors are applied one at a time, and a second descriptor is only used if the first one orders two items as the same. Using -intValue to order the items lets you use a single sort descriptor that will order the items the way you want.
Do this instead:
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"intValue" ascending:YES];
[arr sortedArrayUsingDescriptors:@[sortDescriptor]];
来源：https://stackoverflow.com/questions/24331566/objective-c-sort-an-array-of-strings-containing-numbers