Added dateByAddingSeconds and dateBySubtractingSeconds

Fix melvitax#21

AFDateHelper/AFDateExtension.swift

@@ -405,7 +405,7 @@ public extension NSDate {
     }
 
     /**
-    Returns a new NSDate object by a adding minutes.
+    Returns a new NSDate object by a substracting minutes.
     
     :param: days :Int Minutes to add.
     :returns: NSDate
@@ -417,6 +417,32 @@ public extension NSDate {
         return NSCalendar.currentCalendar().dateByAddingComponents(dateComp, toDate: self, options: NSCalendarOptions(rawValue: 0))!
     }
 
+    /**
+     Returns a new NSDate object by a adding seconds.
+     
+     :param: Seconds Seconds to add.
+     :returns: NSDate
+     */
+    func dateByAddingSeconds(seconds: Int) -> NSDate
+    {
+        let dateComp = NSDateComponents()
+        dateComp.second = seconds
+        return NSCalendar.currentCalendar().dateByAddingComponents(dateComp, toDate: self, options: NSCalendarOptions(rawValue: 0))!
+    }
+
+    /**
+     Returns a new NSDate object by a substracting seconds.
+     
+     :param: days :Int Seconds to substract.
+     :returns: NSDate
+     */
+    func dateBySubtractingSeconds(seconds: Int) -> NSDate
+    {
+        let dateComp = NSDateComponents()
+        dateComp.second = (seconds * -1)
+        return NSCalendar.currentCalendar().dateByAddingComponents(dateComp, toDate: self, options: NSCalendarOptions(rawValue: 0))!
+    }
+
     /**
     Returns a new NSDate object from the start of the day.
     

Demo/ViewController.swift

@@ -181,6 +181,14 @@ class ViewController: UITableViewController {
         date = now.dateBySubtractingMinutes(4)
         sectionItems.append(TableItem(title: "Substracting Minutes", description: "- 4 Minutes: \(date.toString())"))
 
+        // MARK: dateByAddingSeconds
+        date = now.dateByAddingSeconds(90)
+        sectionItems.append(TableItem(title: "Adding Seconds", description: "+ 90 Seconds: \(date.toString())"))
+
+        // MARK: dateBySubstractingSeconds
+        date = now.dateBySubtractingSeconds(90)
+        sectionItems.append(TableItem(title: "Substracting Seconds", description: "- 90 Minutes: \(date.toString())"))
+
         // MARK: dateAtStartOfDay
         date = now.dateAtStartOfDay()
         sectionItems.append(TableItem(title: "Start of Day", description: "\(date.toString())"))