Safe area

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## master
 
+* Adds `tempuraSafeAreaInsets` and `statusBarHeight` as view's properties. See [this pr](https://github.com/BendingSpoons/tempura-lib-swift/pull/7) for more information
+
 ## 0.5.0
 
 * Update to swift 4.0

Tempura/Extensions/ViewControllerModellableView+LayoutGuides.swift

@@ -8,16 +8,64 @@
 
 import Foundation
 
-public extension ViewControllerModellableView {
+// MARK: Layout Helpers
+public extension ViewControllerModellableView where Self: UIView {
+  /**
+   The safe area of a view reflects the area not covered by navigation bars, tab bars, toolbars,
+   and other ancestors that obscure a view controller's view. (In tvOS, the safe area reflects
+   the area not covered by the screen's bezel.) You obtain the safe area for a view by applying the
+   insets in this property to the view's bounds rectangle. If the view is not currently installed in a
+   view hierarchy, or is not yet visible onscreen, the edge insets in this property are 0.
+
+   For the view controller's root view, the insets account for the status bar and other visible bars.
+
+   ## Prior iOS 11
+   The UIKit `safeAreaInsets`'s property is not available prior iOS 11.
+   Tempura creates a similar version of the same property by using values that are available in old
+   versions of iOS. This value, though, is less accurate as it doesn't take into account left/right insets.
+   This shouldn't be an issue as the only device where this may be useful is the iPhone X, which only runs
+   iOS 11 (or newer).
+
+   UIKit properties that may influece the safe area (see iOS 11 section) doesn't work on legacy versions
+   of the system.
+
+   ## iOS 11
+   You can specify for your view controller using the `additionalSafeAreaInsets`property.
+   For other views in the view hierarchy, the insets reflect only the portion of the view that is covered.
+   For example, if a view is entirely within the safe area of its superview,
+   the edge insets in this property are 0.
+
+   - seeAlso: https://developer.apple.com/documentation/uikit/uiview/positioning_content_relative_to_the_safe_area
+   */
+  public var tempuraSafeAreaInsets: UIEdgeInsets {
+    if #available(iOS 11.0, *) {
+      return self.safeAreaInsets
+    } else {
+      return self.legacyIOSSafeAreaInsets
+    }
+  }
+
+  // The current height of the status bar
+  public var statusBarHeight: CGFloat {
+    return UIApplication.shared.statusBarFrame.height
+  }
 
-  public var topInset: CGFloat {
-    let isTranslucent = self.navigationBar?.isTranslucent ?? false
-    var height: CGFloat = 0.0
-    if isTranslucent {
-      let statusBarHeight = UIApplication.shared.statusBarFrame.height
-      let navBarHeight: CGFloat = self.navigationBar?.bounds.size.height ?? 0.0
-      height = statusBarHeight + navBarHeight
+  /**
+   Implementation of te safe area insets for iOS versions < 11.
+   The implementation leverages the view controller's properties.
+
+   - warning: When the vc is not available yet, the insets are zero
+   */
+  private var legacyIOSSafeAreaInsets: UIEdgeInsets {
+    guard let vc = self.viewController else {
+      return .zero
     }
-    return height
+
+    return UIEdgeInsets(
+      top: vc.topLayoutGuide.length,
+      left: 0,
+      bottom: vc.bottomLayoutGuide.length,
+      right: 0
+    )
   }
 }