代表目標中的時間間隔-C

Question

我知道有一種數據類型叫NSTimeInterval，但這是以秒爲單位的。我想要一個能夠表示時間範圍的對象表示，例如6月21日星期四8:00至6月21日星期四9:00。稍後，我想比較當前的日期/時間並檢查它是否適合此範圍。做這個的最好方式是什麼？

Answer 1

我會建議使用兩個NSDate對象來存儲開始和結束日期。您可以輕鬆地確定一個日期是它們之間使用timeIntervalSinceDate:方法：

- (BOOL)dateInInterval:(NSDate *)testDate { 
    // date1 is the instance variable containing the starting date 
    // date2 is the instance variable containing the ending date 
    return ([testDate timeIntervalSinceDate:date1] > 0 && 
      [testDate timeIntervalSinceDate:date2] < 0); 
} 

你只需要做出哪些擁有兩個NSDate的對象，確保第一個是前一秒，並且包括這個方法的類。

僅供參考，NSTimeInterval不是類，它是double的typedef。

編輯

既然你想利用這些作爲一個字典，你可以使用類似這樣的東西來存儲和檢索數據的密鑰：

@protocol IntervalDictionaryKey <NSObject> 
// The class you use as keys for your dictionary must implement this method to determine if a object is in the interval 
- (BOOL)intervalContains:(id)object; 
@end 
@interface IntervalDictionary : NSObject { 
    NSMutableArray *keys, *values; 
} 
- (void)addInterval:(id<IntervalDictionaryKey>)interval withObject:(id)object; 
- (void)setObject:(id)object forIntervalOf:(id)intervalObject; 
- (id)objectForIntervalOf:(id)object; 
@end 


@implementation IntervalDictionary 
- (id)init { 
    if(self = [super init]) { 
     keys = [NSMutableArray new]; 
     values = [NSMutableArray new]; 
    } 
    return self; 
} 
- (void)dealloc { 
    [keys release]; 
    [values release]; 
    [super dealloc]; 
} 
- (void)addInterval:(id<IntervalDictionaryKey>)interval withObject:(id)object { 
    [keys addObject:interval]; 
    [values addObject:object]; 
} 
- (void)setObject:(id)object forIntervalOf:(id)intervalObject { 
    id<IntervalDictionaryKey> key; 
    NSUInteger i = 0; 
    for(key in keys) { 
     if([key intervalContains:intervalObject]) { 
      [values replaceObjectAtIndex:i withObject:object]; 
      break; 
     } 
     ++i; 
    } 
} 
- (id)objectForIntervalOf:(id)object { 
    id<IntervalDictionaryKey> key; 
    NSUInteger i = 0; 
    for(key in keys) { 
     if([key intervalContains:object]) { 
      return [values objectAtIndex:i]; 
     } 
     ++i; 
    } 
} 
@end 

用法：

例間隔等級：

@interface DateInterval : NSObject <IntervalDictionaryKey> { 
    NSDate *date1, *date2; 
} 
- (BOOL)intervalContains:(NSDate *)date; // this is the same as the dateInInterval method above 
@end 
@implementation DateInterval 
// initializer which sets date1 and date2 
- (BOOL)intervalContains:(NSDate *)date { 
    return ([date timeIntervalSinceDate:date1] > 0 && 
      [date timeIntervalSinceDate:date2] < 0); 
} 
@end 

示例用法代碼：

//intervalX is a DateInterval object, created elsewhere 
//objectX is any object, created elsewhere 
//objectInX is a NSDate which is part of intervalX, created elsewhere 
IntervalDictionary *dict = [IntervalDictionary new]; 
[dict addInterval:interval0 withObject:object0]; 
[dict addInterval:interval1 withObject:object1]; 
[dict objectForIntervalOf:objectIn0]; // returns object0 
[dict objectForIntervalOf:objectIn1]; // returns object1 
[dict setObject:object2 forIntervalOf:objectIn1]; // changes the object for interval1 to object2 
[dict objectForIntervalOf:objectIn1]; // now returns object2 

Answer 2

NSDateComponents可以被用來存儲時間間隔的部件以及日期組件。您可以使用NSCalendar的dateByAddingComponents:toDate:options:將這樣的對象添加到NSDate。