add initWithCode and init AXStretchableHeaderTabViewController's view…

Classes/AXStretchableHeaderTabViewController.h

@@ -24,6 +24,9 @@
 @property (weak, nonatomic) IBOutlet UIScrollView *containerView;
 @property (nonatomic) BOOL shouldBounceHeaderView;
 
+// only call after view has appeared
+- (void)switchToIndex:(NSUInteger)index;
+
 // Layout
 - (void)layoutHeaderViewAndTabBar;
 - (void)layoutViewControllers;

Classes/AXStretchableHeaderTabViewController.m

@@ -15,26 +15,48 @@ @implementation AXStretchableHeaderTabViewController {
   CGFloat _headerViewTopConstraintConstant;
 }
 
-- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
+//- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
+//{
+//  // MEMO:
+//  // An inherited class does not load xib file.
+//  // So, this code assigns class name of AXStretchableHeaderTabViewController clearly.
+//  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
+//  if (self) {
+//      
+//  }
+//  return self;
+//}
+
+- (void)switchToIndex:(NSUInteger)index
 {
-  // MEMO:
-  // An inherited class does not load xib file.
-  // So, this code assigns class name of AXStretchableHeaderTabViewController clearly.
-  self = [super initWithNibName:NSStringFromClass([AXStretchableHeaderTabViewController class]) bundle:nibBundleOrNil];
-  if (self) {
-    // Custom initialization
-    _shouldBounceHeaderView = YES;
-
-    _tabBar = [[AXTabBar alloc] init];
-    [_tabBar setDelegate:self];
-  }
-  return self;
+    if (self.viewControllers == nil
+        || index >= self.viewControllers.count)
+        return;
+    
+    self.tabBar.selectedItem = self.tabBar.items[index];
+    [self.containerView setContentOffset:(CGPoint) { index *CGRectGetWidth(
+                                                                           self.containerView
+                                                                           .bounds),
+        self.containerView
+        .contentOffset
+        .y } animated:YES];
+    self.selectedIndex = index;
 }
 
 - (void)viewDidLoad
 {
   [super viewDidLoad];
-
+
+  // Custom initialization
+  [[NSBundle mainBundle] loadNibNamed:NSStringFromClass([AXStretchableHeaderTabViewController class]) owner:self options:nil];
+
+  _shouldBounceHeaderView = YES;
+
+  if (!_tabBar) {
+    _tabBar = [[AXTabBar alloc] init];
+  }
+
+  [_tabBar setDelegate:self];
   [_tabBar sizeToFit];
   [self.view addSubview:_tabBar];
 }

Classes/AXTabBar.m

@@ -23,6 +23,22 @@ - (id)initWithFrame:(CGRect)frame
 {
   self = [super initWithFrame:frame];
   if (self) {
+      [self commonInit];
+  }
+  return self;
+}
+
+-(id)initWithCoder:(NSCoder *)aDecoder
+{
+    self = [super initWithCoder:aDecoder];
+    if (self) {
+        [self commonInit];
+    }
+    return self;
+}
+
+-(void)commonInit
+{
     _tabBarButtonFont = [UIFont systemFontOfSize:14.0];
 
     _toolbar = [[UIToolbar alloc] init];
@@ -38,11 +54,9 @@ - (id)initWithFrame:(CGRect)frame
     _bottomSeparator = [CALayer layer];
     [_bottomSeparator setBackgroundColor:[[UIColor colorWithWhite:0.0 alpha:0.1] CGColor]];
     [self.layer addSublayer:_bottomSeparator];
-
+    
     _indicatorLayer = [CALayer layer];
     [self.layer addSublayer:_indicatorLayer];
-  }
-  return self;
 }
 
 - (void)layoutSubviews

Classes/AXTabBarItemButton.m

@@ -12,11 +12,25 @@ - (id)initWithFrame:(CGRect)frame
   self = [super initWithFrame:frame];
   if (self) {
     // Initialization code
+      [self commonInit];
+  }
+  return self;
+}
+
+-(id)initWithCoder:(NSCoder *)aDecoder
+{
+    self = [super initWithCoder:aDecoder];
+    if (self) {
+        [self commonInit];
+    }
+    return self;
+}
+
+-(void)commonInit
+{
     [self setTitleColor:[UIColor darkTextColor] forState:UIControlStateNormal];
     [self setTitleColor:[UIColor orangeColor] forState:UIControlStateSelected];
     [self setTitleColor:[UIColor orangeColor] forState:UIControlStateHighlighted];
-  }
-  return self;
 }
 
 - (void)layoutSubviews