如何对包含NSDictionaries的NSArray进行排序？

NSArray *array = @[@{@"key": @(4)}, @{@"key": @(1)}, @{@"key": @(3)}, @{@"key": @(2)}];
NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSNumber *valueA = [a objectForKey:@"key"];
    NSNumber *valueB = [b objectForKey:@"key"];
    return [valueA compare:valueB];
}];

let array: [NSDictionary] = [["key": 4], ["key": 1], ["key": 3], ["key": 2]]
let sortedArray = array.sorted { (a, b) -> Bool in
    let valueA = a["key"] as! Int
    let valueB = b["key"] as! Int
    return valueA< valueB
}