将视图内左右间距参数开放出来，在一屏多图滑动时可在外部设置距离，不设置使用默认居中展示

Sources/FSPageViewLayout.swift

@@ -75,7 +75,15 @@ class FSPagerViewLayout: UICollectionViewLayout {
             return pagerView.interitemSpacing
         }()
         self.scrollDirection = pagerView.scrollDirection
-        self.leadingSpacing = self.scrollDirection == .horizontal ? (collectionView.frame.width-self.actualItemSize.width)*0.5 : (collectionView.frame.height-self.actualItemSize.height)*0.5
+
+        self.leadingSpacing = {
+            var spacing = pagerView.leadingSpacing
+            if spacing == .zero {
+                spacing = self.scrollDirection == .horizontal ? (collectionView.frame.width-self.actualItemSize.width)*0.5 : (collectionView.frame.height-self.actualItemSize.height)*0.5
+            }
+            return spacing
+        }()
+
         self.itemSpacing = (self.scrollDirection == .horizontal ? self.actualItemSize.width : self.actualItemSize.height) + self.actualInteritemSpacing
 
         // Calculate and cache contentSize, rather than calculating each time

Sources/FSPagerView.swift

@@ -192,6 +192,14 @@ open class FSPagerView: UIView,UICollectionViewDataSource,UICollectionViewDelega
         }
     }
 
+    /// The spacing to use leading items in the pager view. Default is 0.
+    @IBInspectable
+    open var leadingSpacing: CGFloat = 0 {
+        didSet {
+            self.collectionViewLayout.forceInvalidate()
+        }
+    }
+
     // MARK: - Public readonly-properties
 
     /// Returns whether the user has touched the content to initiate scrolling.