swift - @distinctUnionOfObjects 在 Swift 中可用吗？

Question

我正在尝试从 this 开始快速制作日历很好的例子。到目前为止，我设法显示了网格和所有自定义 UICollectionViewLayout 的补充 View 。问题是当我试图在日历中添加事件时。日行和日历都在同一个 NSMutableDictionary 中，它有一个使用此格式 2016-10-12 表示日期(字符串)的键。 objective-c 代码是

-(void)groupEventsBySection{
   //toDeviceTimezoneDateString simply take a Date and make a string
_eventsBySection = [mEvents groupBy:@"StartDate.toDeviceTimezoneDateString"].mutableCopy;
     // after groupBy is performed _eventsBySection contains only those keys found in mEvents with inside an array of objects {
   // "2016-10-12" =     (
   // "<MSEvent: 0x60000004a680>",
   // "<MSEvent: 0x60000004a380>");
   // "2016-10-13" =     (
   // "<MSEvent: 0x600000049b10>");
   // "2016-10-17" =     (
   // "<MSEvent: 0x600000049fc0>");
   //  }  

NSDate* date = [NSDate today:@"device"]; // today's date
if(self.daysToShow == 1 && _eventsBySection.count == 1){
    date = [NSDate parse:_eventsBySection.allKeys.firstObject];
}
 //here it adds the remaining "daysToShow" if the key doesn't already exist in the MutableDictionary. 
for(int i = 0; i< self.daysToShow; i++){
    if(![_eventsBySection.allKeys containsObject:date.toDeviceTimezoneDateString]){
        [_eventsBySection setObject:@[] forKey:date.toDeviceTimezoneDateString];
    }
    date = [date addDay]; // this just add one day to date 
 }
}

到此为止已经很清楚了。问题是当我尝试更改 objective-c 中的 groupBy 函数时:

- (NSDictionary*)groupBy:(NSString*)keypath{
return [self groupBy:keypath block:^NSString *(id object, NSString *key) {
    return key;
}];
}

- (NSDictionary*)groupBy:(NSString*)keypath block:(NSString*(^)(id object, NSString* key))block{
    NSMutableDictionary *result = [NSMutableDictionary new];
    NSString* finalKeypath = [NSString stringWithFormat:@"%@.@distinctUnionOfObjects.self",keypath];
    NSArray *distinct = [self valueForKeyPath:finalKeypath];

    [distinct each:^(NSString* value) {
        NSPredicate *predicate  = [NSPredicate predicateWithFormat:@"%K = %@", keypath,value];
        NSArray *objects        = [self filteredArrayUsingPredicate:predicate];
        [result setObject:objects forKey:block(objects[0],value)];
    }];
        return result;
}

- (NSDictionary*)expand:(NSString*)keypath{
    return [self expand:keypath unique:NO];
}

到目前为止，这是我在 swift 中所做的:

我有这个类，在原始代码中是 MSEvent

class Event : NSObject {

var title:String?
var location:String?
var startTime:Date?
var endTime:Date?
var duration:Int?
var subtitle:String?

 init(startTime: Date, duration: Int, title: String, subtitle: String) {
    super.init()
    self.startTime = startTime
    self.duration = duration
    self.title = title
    self.subtitle = subtitle

}

我创建了一些假事件:

override func viewDidLoad() {
        let today = Date()
        let event1 = Event(startTime: today, duration: 60, title: "prova", subtitle: "HEllo")
        let event2 = Event(startTime: today, duration: 60, title: "prova", subtitle: "HEllo")
        let event3 = Event(startTime: today.dateByAddingDays(days: 1), duration: 60, title: "prova", subtitle: "HEllo")

        var array:[Event] = []
        array.append(event1)
        array.append(event2)
        array.append(event3)

        calendarView.setEvents(events: array)
 }

func setEvents(events:[Event]){

    mEvents = events as NSArray    
    print(mEvents)
    //this right now returns the 3 event objects I added:
    // (
    // "<myapp.Event: 0x60800032ba40>",
   //  "<myapp.Event: 0x60800032bae0>",
   //  "<myapp.Event: 0x60800032bcc0>"
   //  )
    self.forceReload(reloadEvent: true) //force reload eventually call the groupEventsBy days
}


func groupEventsByDays(){
    // of course everything works without the next line of code 
    eventsBySection = mEvents.groupBy(keypath:  "startTime").mutableCopy() as! NSMutableDictionary
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd"
    var date = dateFormatter.date(from: "2016-10-01")
                  // right now daysToShow is equal to 30
            for _ in 0..<daysToShow{

        eventsBySection.setObject([], forKey: self.setFormatDate(date: date!) as NSCopying)


        date = self.addDay(date: date!)

    }
}

问题来了。这是我的扩展。 扩展 NSArray{

    func groupBy(keypath:NSString)->NSDictionary{

        return self.groupBy(keypath: keypath, block: { (object, key) -> NSString in
            return key
        })
    }

    func groupBy(keypath:NSString,block:@escaping ((_ object: Any, _ key:NSString )-> NSString))-> NSDictionary{

        let result:NSMutableDictionary = NSMutableDictionary()

        let finalKeypath = String.localizedStringWithFormat("%@.distinctUnionOfObjects.self", keypath)
        let distinct:NSArray = self.value(forKey: finalKeypath) as! NSArray

        (distinct as AnyObject).each(operation: { (value) in
            let predicate = NSPredicate(format: "%K = %@", keypath,value as! CVarArg)
            let objects = self.filtered(using: predicate)
            result.setObject(objects, forKey: (block(objects[0], value as! NSString)))

            })

        return result;
    }

    func each(operation:@escaping ((_ object: AnyObject)-> Void)){

        self.enumerateObjects({ (object, idx, stop) in
            operation(object as AnyObject)
        })

    }
}

它崩溃并出现错误 此类不符合键 startTitle.distinctUnionOfObjects.self 的键值编码。'我试过像这样使用 map

       let startDate = array.map ({ $0.startTime })

我设法获取了所有日期(虽然没有明显区别)，但我不知道如何使用 swift 实现上述代码中显示的相同结果。

Answer 1

我终于设法完成了上述 objective-c 代码使用 @distinctUnionOfObjects.sel 所做的事情。不过，我不太确定这是一种优雅的方式。欢迎所有评论或更好的答案。

extension Collection {
    func find( predicate: (Self.Iterator.Element) throws -> Bool) rethrows -> Self.Iterator.Element? {
        return try index(where: predicate).map({self[$0]})
    }
}

override func viewDidLoad() {
    super.viewDidLoad()

let event1 = Event(startTime: today!, duration: 60, title: "prova", subtitle: "HEllo")
let event2 = Event(startTime: (today?.dateByAddingDays(days: 5))!, duration: 60, title: "prova", subtitle: "HEllo")
let event3 = Event(startTime: (today?.dateByAddingDays(days: 1))!, duration: 60, title: "prova", subtitle: "HEllo")
let event4 = Event(startTime: todayLater!, duration: 60, title: "prova", subtitle: "HEllo")

var array:[Event] = []
array.append(event1)
array.append(event2)
array.append(event3)
array.append(event4)

 // I create an array with all the date/startTime
let startTime = array.map ({ $0.startTime })

let dict:NSMutableDictionary = [:]

   for date in startTime {
             //find the objects for that date
            let object =  array.find(predicate: {$0.startTime?.toDeviceDateString() == date?.toDeviceDateString()})
           //check if that key/date exist in the dictionary 
        if var val:[Event] = dict[(date?.setFormatDate())!] as! [Event]? {
               //if it does I simply add the object to the array 
            val.append(object!)
            dict.setObject(val, forKey: date?.setFormatDate() as! NSCopying)

        } else {
            print("key is not present in dict")
            //otherwise I add a new array with that object inside for the date/key
            dict.setObject([object], forKey: date?.setFormatDate() as! NSCopying)
        }


    }

  calendarView.setEvents(events: dict)
 }

func setEvents(events:NSMutableDictionary){ 
//slots events hold the events objects
slotEvents = events
self.forceReload(reloadEvent: true)

}


 func groupEventsByDays(){


let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
var date = dateFormatter.date(from: "2016-10-01")

for _ in 0..<daysToShow{

    if let val:[Event] = slotEvents[(date?.setFormatDate())!] as! [Event]? {

        eventsBySection.setObject(val, forKey: date?.setFormatDate() as! NSCopying)

    }else{

        eventsBySection.setObject([], forKey: date?.setFormatDate() as! NSCopying)

    }

    date = self.addDay(date: date!)

}
 print("after\(eventsBySection)")
  //Which print 
  //{
 //"2016-10-01" =     (
 // );
//"2016-10-02" =     (
 // );
 // "2016-10-03" =     (
 //     "Optional(<myapp.Event: 0x6000001242e0>)",
 //     "<myapp.Event: 0x6000001242e0>"
//  );
//  "2016-10-04" =     (
//      "Optional(<myapp.Event: 0x600000124600>)"
//  );
//  "2016-10-05" =     (
//   );
//   "2016-10-06" =     (
//   );
//   "2016-10-07" =     (
//   );
//   "2016-10-08" =     (
//       "Optional(<myapp.Event: 0x600000124240>)"
//   );
//  "2016-10-09" =     (
 //   );
  //.... and so on up to 30 days

}