Adding PNScatterChart - DataItem

+//
+//  PNScatterChartDataItem.h
+//  PNChartDemo
+//
+//  Created by Alireza Arabi on 12/4/14.
+//  Copyright (c) 2014 kevinzhow. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+@interface PNScatterChartDataItem : NSObject
+
++ (PNScatterChartDataItem *)dataItemWithX:(CGFloat)x AndWithY:(CGFloat)y;
+
+@property (readonly) CGFloat x; // should be within the x range
+@property (readonly) CGFloat y; // should be within the y range
+
+@end

+//
+//  PNScatterChartDataItem.m
+//  PNChartDemo
+//
+//  Created by Alireza Arabi on 12/4/14.
+//  Copyright (c) 2014 kevinzhow. All rights reserved.
+//
+
+#import "PNScatterChartDataItem.h"
+
+@interface PNScatterChartDataItem ()
+
+- (id)initWithX:(CGFloat)x AndWithY:(CGFloat)y;
+
+@property (readwrite) CGFloat x; // should be within the x range
+@property (readwrite) CGFloat y; // should be within the y range
+
+@end
+
+@implementation PNScatterChartDataItem
+
++ (PNScatterChartDataItem *)dataItemWithX:(CGFloat)x AndWithY:(CGFloat)y
+{
+    return [[PNScatterChartDataItem alloc] initWithX:x AndWithY:y];
+}
+
+- (id)initWithX:(CGFloat)x AndWithY:(CGFloat)y
+{
+    if ((self = [super init])) {
+        self.x = x;
+        self.y = y;
+    }
+    
+    return self;
+}
+
+@end