Add support to iOS 11 and 12.

LTNavigationBar/UINavigationBar+Awesome.m

@@ -6,13 +6,34 @@
 //  Copyright (c) 2015 ltebean. All rights reserved.
 //
 
-#import "UINavigationBar+Awesome.h"
 #import <objc/runtime.h>
+#import "UINavigationBar+Awesome.h"
 
 #define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
 
 @implementation UINavigationBar (Awesome)
 static char overlayKey;
+static char queuedBackgroundColorKey;
+
++ (void)load
+{
+#if !TARGET_INTERFACE_BUILDER
+    //swizzle method didMoveToWindow
+    Class class = [self class];
+
+    SEL originalSelector = @selector(didMoveToWindow);
+    SEL swizzledSelector = @selector(lt_DidMoveToWindow);
+    Method originalMethod = class_getInstanceMethod(class, originalSelector);
+    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
+
+    BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
+    if (didAddMethod) {
+        class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
+    } else {
+        method_exchangeImplementations(originalMethod, swizzledMethod);
+    }
+#endif
+}
 
 - (UIView *)overlay
 {
@@ -24,16 +45,74 @@ - (void)setOverlay:(UIView *)overlay
     objc_setAssociatedObject(self, &overlayKey, overlay, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
 }
 
+- (UIColor *)queuedBackgroundColor
+{
+    return objc_getAssociatedObject(self, &queuedBackgroundColorKey);
+}
+
+- (void)setQueuedBackgroundColor:(UIColor *)color
+{
+    objc_setAssociatedObject(self, &queuedBackgroundColorKey, color, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
 - (void)lt_setBackgroundColor:(UIColor *)backgroundColor
 {
-    if (!self.overlay) {
-        [self setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
-        self.overlay = [[UIView alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds) + 20)];
-        self.overlay.userInteractionEnabled = NO;
-        self.overlay.autoresizingMask = UIViewAutoresizingFlexibleWidth;    // Should not set `UIViewAutoresizingFlexibleHeight`
-        [[self.subviews firstObject] insertSubview:self.overlay atIndex:0];
+    //for better performance, minimize call self.overlay
+    UIView *bgOverlay = self.overlay;
+    if (!bgOverlay)
+    {
+        if (self.subviews.count == 0)
+        {
+            /*We call layoutIfNeeded to force subviews to be created. However, it only work for iOS 11 and below.
+              For iOS 12, the subviews of navigation bar is created after navigation bar didMoveToWindow,
+              so we need to swizzle didMoveToWindow method, see class method + (void)load */
+            [self layoutIfNeeded];
+        }
+
+        if (self.subviews.count > 0)
+        {
+            [self setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
+
+            bgOverlay = [[UIView alloc] initWithFrame:[self.subviews firstObject].bounds];
+            bgOverlay.userInteractionEnabled = NO;
+            bgOverlay.translatesAutoresizingMaskIntoConstraints = NO;
+            //[self.subviews firstObject] is _UIBarBackground
+            [[self.subviews firstObject] insertSubview:bgOverlay atIndex:0];
+
+            //_UIBarBackground's frame can be changed, so we use auto layout
+            CGFloat topOffset = 0;
+            if (SYSTEM_VERSION_LESS_THAN(@"11.0"))
+            {
+                /*For iOS below 11.0, the _UIBarBackground of standalone UINavigationBar
+                  won't extend to status bar, so we do it manually. BUT what if UINavigationBar
+                  is in a UINavigationController, don't worry, -20 does no harm.
+                /*/
+                topOffset = -20;
+            }
+            NSString *vVisualFormat = [NSString stringWithFormat:@"V:|-(%i)-[overlay]-(0)-|", (int)topOffset];
+            NSArray *vConstraints = [NSLayoutConstraint constraintsWithVisualFormat:vVisualFormat
+                                                                            options:0
+                                                                            metrics:nil
+                                                                              views:@{@"overlay":bgOverlay}];
+            NSArray *hConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(0)-[overlay]-(0)-|"
+                                                                            options:0
+                                                                            metrics:nil
+                                                                              views:@{@"overlay":bgOverlay}];
+            [bgOverlay.superview addConstraints:vConstraints];
+            [bgOverlay.superview addConstraints:hConstraints];
+
+            self.overlay = bgOverlay;
+        }
+    }
+
+    if (bgOverlay)
+    {
+        bgOverlay.backgroundColor = backgroundColor;
+    }
+    else
+    {
+        self.queuedBackgroundColor = backgroundColor;
     }
-    self.overlay.backgroundColor = backgroundColor;
 }
 
 - (void)lt_setTranslationY:(CGFloat)translationY
@@ -43,25 +122,63 @@ - (void)lt_setTranslationY:(CGFloat)translationY
 
 - (void)lt_setElementsAlpha:(CGFloat)alpha
 {
-    [[self valueForKey:@"_leftViews"] enumerateObjectsUsingBlock:^(UIView *view, NSUInteger i, BOOL *stop) {
-        view.alpha = alpha;
-    }];
-
-    [[self valueForKey:@"_rightViews"] enumerateObjectsUsingBlock:^(UIView *view, NSUInteger i, BOOL *stop) {
-        view.alpha = alpha;
-    }];
-
-    UIView *titleView = [self valueForKey:@"_titleView"];
-    titleView.alpha = alpha;
-//    when viewController first load, the titleView maybe nil
-    [[self subviews] enumerateObjectsUsingBlock:^(UIView *obj, NSUInteger idx, BOOL *stop) {
-        if ([obj isKindOfClass:NSClassFromString(@"UINavigationItemView")]) {
-            obj.alpha = alpha;
-        }
-        if ([obj isKindOfClass:NSClassFromString(@"_UINavigationBarBackIndicatorView")]) {
-            obj.alpha = alpha;
-        }
-    }];
+    if (SYSTEM_VERSION_LESS_THAN(@"11.0"))
+    {
+        [[self valueForKey:@"_leftViews"] enumerateObjectsUsingBlock:^(UIView *view, NSUInteger i, BOOL *stop) {
+            view.alpha = alpha;
+        }];
+
+        [[self valueForKey:@"_rightViews"] enumerateObjectsUsingBlock:^(UIView *view, NSUInteger i, BOOL *stop) {
+            view.alpha = alpha;
+        }];
+
+        UIView *titleView = [self valueForKey:@"_titleView"];
+        titleView.alpha = alpha;
+        //when viewController first load, the titleView maybe nil
+        [[self subviews] enumerateObjectsUsingBlock:^(UIView *obj, NSUInteger idx, BOOL *stop) {
+            if ([obj isKindOfClass:NSClassFromString(@"UINavigationItemView")]) {
+                obj.alpha = alpha;
+            }
+            else if ([obj isKindOfClass:NSClassFromString(@"_UINavigationBarBackIndicatorView")]) {
+                obj.alpha = alpha;
+            }
+        }];
+    }
+    else
+    {
+        [[self subviews] enumerateObjectsUsingBlock:^(UIView *obj, NSUInteger idx, BOOL *stop) {
+            if (![obj isKindOfClass:NSClassFromString(@"_UIBarBackground")])
+            {
+                //_UINavigationBarLargeTitleView, _UINavigationBarContentView, _UINavigationBarModernPromptView
+                if ([obj isKindOfClass:NSClassFromString(@"_UINavigationBarContentView")])
+                {
+                    [[obj subviews] enumerateObjectsUsingBlock:^(UIView *subObj, NSUInteger idx, BOOL *stop) {
+                        if (![subObj isKindOfClass:[UILabel class]])
+                        {
+                            subObj.alpha = alpha;
+                        }
+                        else
+                        {
+                            [self lt_setTitleLabelAlpha:alpha titleLabel:(UILabel*)subObj];
+                        }
+                    }];
+                }
+                else
+                {
+                    if (obj.subviews.count > 0)
+                    {
+                        [[obj subviews] enumerateObjectsUsingBlock:^(UIView *subObj, NSUInteger idx, BOOL *stop) {
+                            subObj.alpha = alpha;
+                        }];
+                    }
+                    else
+                    {
+                        obj.alpha = alpha;
+                    }
+                }
+            }
+        }];
+    }
 }
 
 - (void)lt_reset
@@ -71,4 +188,47 @@ - (void)lt_reset
     self.overlay = nil;
 }
 
+- (void)lt_DidMoveToWindow
+{
+    [self lt_DidMoveToWindow];
+    UIColor *queuedColor = self.queuedBackgroundColor;
+    if (queuedColor != nil)
+    {
+        if (self.subviews.count == 0)
+        {
+            [self layoutSubviews];
+        }
+
+        if (self.subviews.count > 0)
+        {
+            [self lt_setBackgroundColor:queuedColor];
+            self.queuedBackgroundColor = nil;
+        }
+    }
+}
+
+//set the alpha value of title label by set text color
+- (void)lt_setTitleLabelAlpha:(CGFloat)alpha titleLabel:(UILabel*)label
+{
+    NSDictionary *attr = [self titleTextAttributes];
+    UIColor *textColor = [attr valueForKey:NSForegroundColorAttributeName];
+    if (textColor == nil)
+    {
+        textColor = label.textColor;
+    }
+    if (textColor == nil)
+    {
+        textColor = [UIColor blackColor];
+    }
+    textColor = [textColor colorWithAlphaComponent:alpha];
+
+    NSMutableDictionary *newAttr = [[NSMutableDictionary alloc] initWithCapacity:attr.count + 1];
+    if (attr.count > 0)
+    {
+        [newAttr addEntriesFromDictionary:attr];
+    }
+    [newAttr setObject:textColor forKey:NSForegroundColorAttributeName];
+    [self setTitleTextAttributes:newAttr];
+}
+
 @end