IDC资讯中心
项目介绍：
1. 要实现以下这些效果都非常简单
2. 废话不多说，先看看实现效果
3. 下面告诉你我为什么说实现这些效果非常简单
比如说要实现蚂蚁森林的导航栏效果(有以下几个需求)：
-
刚进入导航栏透明、两边按钮和文字都是白色、状态栏也是白色
-
向上滚动后导航栏背景由透明逐渐变成白色
-
当超过某一点后，标题变成黑色、状态栏变成黑色、两边按钮变成蓝色
实现步骤：
3.1. 实现刚进入导航栏透明、两边按钮和文字都是白色、状态栏也是白色
- (void)viewDidLoad
{
[super viewDidLoad];
// 设置导航栏颜色为白色
[self wr_setNavBarBarTintColor:[UIColor whiteColor]];
// 设置导航栏透明度为0
[self wr_setNavBarBackgroundAlpha:0];
}3.2. 实现剩下两个需求
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat offsetY = scrollView.contentOffset.y;
if (offsetY > NAVBAR_COLORCHANGE_POINT)
{
CGFloat alpha = (offsetY - NAVBAR_COLORCHANGE_POINT) / NAV_HEIGHT;
// 向上滚动后导航栏背景由透明逐渐变成白色
[self wr_setNavBarBackgroundAlpha:alpha];
if (alpha > 0.5) {
// 当超过某一点后，两边按钮变成蓝色
[self wr_setNavBarTintColor:[UIColor colorWithRed:0 green:0.478431 blue:1 alpha:1.0]];
// 标题变成黑色
[self wr_setNavBarTitleColor:[UIColor blackColor]];
// 状态栏变成黑色
[self wr_setStatusBarStyle:UIStatusBarStyleDefault];
} else {
// 当没有超过某点，上面属性还原
[self wr_setNavBarTintColor:[UIColor whiteColor]];
[self wr_setNavBarTitleColor:[UIColor whiteColor]];
[self wr_setStatusBarStyle:UIStatusBarStyleLightContent];
}
}
else
{
[self wr_setNavBarBackgroundAlpha:0];
[self wr_setNavBarTintColor:[UIColor whiteColor]];
[self wr_setNavBarTitleColor:[UIColor whiteColor]];
[self wr_setStatusBarStyle:UIStatusBarStyleLightContent];
}
}3.3. 发现没有，改变相关属性只要一句代码就完全搞定了！！！
// 一行代码搞定导航栏颜色
[self wr_setNavBarBarTintColor:[UIColor whiteColor]];
// 一行代码搞定导航栏透明度
[self wr_setNavBarBackgroundAlpha:alpha];
// 一行代码搞定导航栏两边按钮颜色
[self wr_setNavBarTintColor:[UIColor whiteColor]];
// 一行代码搞定导航栏上标题颜色
[self wr_setNavBarTitleColor:[UIColor whiteColor]];
// 一行代码搞定状态栏是 default 还是 lightContent
[self wr_setStatusBarStyle:UIStatusBarStyleLightContent];3.4. 说了这么多，看看几句代码能否实现我们需要的效果吧
3.5. 有人可能会问：这只是在一个界面里面，但是涉及到push、pop、右滑手势怎么办呢？
答：没关系，我已经给你处理好了，你不用写一句代码！！！那么看看效果吧
4. 好了，说了这么多接下来看看如何实现的吧
4.1 实现导航栏透明渐变就很简单了，网上一找一大堆，大部分都是通过加一层的方法来实现（在这里就是加一个view到navigationBar上）
// set navigationBar barTintColor
- (void)wr_setBackgroundColor:(UIColor *)color
{
if (self.backgroundView == nil)
{
// add a image(nil color) to _UIBarBackground make it clear
[self setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
self.backgroundView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.bounds), kWRNavBarBottom)];
// _UIBarBackground is first subView for navigationBar
[self.subviews.firstObject insertSubview:self.backgroundView atIndex:0];
}
self.backgroundView.backgroundColor = color;
}
// set _UIBarBackground alpha (_UIBarBackground subviews alpha <= _UIBarBackground alpha)
- (void)wr_setBackgroundAlpha:(CGFloat)alpha
{
UIView *barBackgroundView = self.subviews.firstObject;
barBackgroundView.alpha = alpha;
}4.2 你以为就这样结束了吗，来看看下面的问题，当由透明的导航栏右滑到不透明的导航栏看看会出现什么情况？
4.3 处理右滑返回手势问题
我们都知道，导航栏是属于导航控制器的，一个导航栏不可能出现两个颜色，那么右滑突兀怎么解决呢？两个方法，一个方法是自定义导航栏（后面会说），另一个方法是改变导航栏颜色，我们假设当前控制器为fromVC，返回的控制器为toVC，如果可以实现从 fromVC 右滑到 toVC 导航栏颜色渐变那么问题就解决了！但是导航栏只有一个颜色啊~~~怎么办？
同样，可以通过加一层的方法来解决。我们可以记录一下 fromVC消失前对应的导航栏颜色 和 toVC 当前的导航栏颜色，然后根据右滑进度percentComplete，来计算渐变色，这样问题就解决了！
记录ViewController对应导航栏的颜色和透明度
// navigationBar barTintColor
- (UIColor *)wr_navBarBarTintColor
{
UIColor *barTintColor = (UIColor *)objc_getAssociatedObject(self, &kWRNavBarBarTintColorKey);
return (barTintColor != nil) ? barTintColor : [UIColor defaultNavBarBarTintColor];
}
- (void)wr_setNavBarBarTintColor:(UIColor *)color
{
objc_setAssociatedObject(self, &kWRNavBarBarTintColorKey, color, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
if ([[self wr_customNavBar] isKindOfClass:[UINavigationBar class]])
{
UINavigationBar *navBar = (UINavigationBar *)[self wr_customNavBar];
[navBar wr_setBackgroundColor:color];
}
else
{
if ([self pushToCurrentVCFinished] == YES && [self pushToNextVCFinished] == NO) {
[self.navigationController setNeedsNavigationBarUpdateForBarTintColor:color];
}
}
}
// navigationBar _UIBarBackground alpha
- (CGFloat)wr_navBarBackgroundAlpha
{
id barBackgroundAlpha = objc_getAssociatedObject(self, &kWRNavBarBackgroundAlphaKey);
return (barBackgroundAlpha != nil) ? [barBackgroundAlpha floatValue] : [UIColor defaultNavBarBackgroundAlpha];
}
- (void)wr_setNavBarBackgroundAlpha:(CGFloat)alpha
{
objc_setAssociatedObject(self, &kWRNavBarBackgroundAlphaKey, @(alpha), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
if ([[self wr_customNavBar] isKindOfClass:[UINavigationBar class]])
{
UINavigationBar *navBar = (UINavigationBar *)[self wr_customNavBar];
[navBar wr_setBackgroundAlpha:alpha];
}
else
{
if ([self pushToCurrentVCFinished] == YES && [self pushToNextVCFinished] == NO) {
[self.navigationController setNeedsNavigationBarUpdateForBarBackgroundAlpha:alpha];
}
}
}交换系统方法 _updateInteractiveTransition（监控右滑返回手势的进度）
// swizzling system method: _updateInteractiveTransition
- (void)wr_updateInteractiveTransition:(CGFloat)percentComplete
{
UIViewController *fromVC = [self.topViewController.transitionCoordinator viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toVC = [self.topViewController.transitionCoordinator viewControllerForKey:UITransitionContextToViewControllerKey];
[self updateNavigationBarWithFromVC:fromVC toVC:toVC progress:percentComplete];
[self wr_updateInteractiveTransition:percentComplete];
}根据 fromVC 与 toVC 的导航栏颜色 配合 返回手势进度计算渐变色
+ (UIColor *)middleColor:(UIColor *)fromColor toColor:(UIColor *)toColor percent:(CGFloat)percent
{
CGFloat fromRed = 0;
CGFloat fromGreen = 0;
CGFloat fromBlue = 0;
CGFloat fromAlpha = 0;
[fromColor getRed:&fromRed green:&fromGreen blue:&fromBlue alpha:&fromAlpha];
CGFloat toRed = 0;
CGFloat toGreen = 0;
CGFloat toBlue = 0;
CGFloat toAlpha = 0;
[toColor getRed:&toRed green:&toGreen blue:&toBlue alpha:&toAlpha];
CGFloat newRed = fromRed + (toRed - fromRed) * percent;
CGFloat newGreen = fromGreen + (toGreen - fromGreen) * percent;
CGFloat newBlue = fromBlue + (toBlue - fromBlue) * percent;
CGFloat newAlpha = fromAlpha + (toAlpha - fromAlpha) * percent;
return [UIColor colorWithRed:newRed green:newGreen blue:newBlue alpha:newAlpha];
}改变导航栏颜色和透明度
- (void)updateNavigationBarWithFromVC:(UIViewController *)fromVC toVC:(UIViewController *)toVC progress:(CGFloat)progress
{
// change navBarBarTintColor
UIColor *fromBarTintColor = [fromVC wr_navBarBarTintColor];
UIColor *toBarTintColor = [toVC wr_navBarBarTintColor];
UIColor *newBarTintColor = [UIColor middleColor:fromBarTintColor toColor:toBarTintColor percent:progress];
[self setNeedsNavigationBarUpdateForBarTintColor:newBarTintColor];
// change navBarTintColor
UIColor *fromTintColor = [fromVC wr_navBarTintColor];
UIColor *toTintColor = [toVC wr_navBarTintColor];
UIColor *newTintColor = [UIColor middleColor:fromTintColor toColor:toTintColor percent:progress];
[self setNeedsNavigationBarUpdateForTintColor:newTintColor];
// change navBarTitleColor
UIColor *fromTitleColor = [fromVC wr_navBarTitleColor];
UIColor *toTitleColor = [toVC wr_navBarTitleColor];
UIColor *newTitleColor = [UIColor middleColor:fromTitleColor toColor:toTitleColor percent:progress];
[self setNeedsNavigationBarUpdateForTitleColor:newTitleColor];
// change navBar _UIBarBackground alpha
CGFloat fromBarBackgroundAlpha = [fromVC wr_navBarBackgroundAlpha];
CGFloat toBarBackgroundAlpha = [toVC wr_navBarBackgroundAlpha];
CGFloat newBarBackgroundAlpha = [UIColor middleAlpha:fromBarBackgroundAlpha toAlpha:toBarBackgroundAlpha percent:progress];
[self setNeedsNavigationBarUpdateForBarBackgroundAlpha:newBarBackgroundAlpha];
}好了！来看看处理后的效果吧，是不是好多了呢~
4.5 咱们来处理右滑返回手势中断的问题吧~
通过遵守UINavigationBarDelegate协议，实现
optional public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool // same as push methods 方法来监听右滑返回手势中断的情况
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item
{
__weak typeof (self) weakSelf = self;
id<UIViewControllerTransitionCoordinator> coor = [self.topViewController transitionCoordinator];
if ([coor initiallyInteractive] == YES)
{
NSString *sysVersion = [[UIDevice currentDevice] systemVersion];
if ([sysVersion floatValue] >= 10)
{
[coor notifyWhenInteractionChangesUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
__strong typeof (self) pThis = weakSelf;
[pThis dealInteractionChanges:context];
}];
}
else
{
[coor notifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
__strong typeof (self) pThis = weakSelf;
[pThis dealInteractionChanges:context];
}];
}
return YES;
}
NSUInteger itemCount = self.navigationBar.items.count;
NSUInteger n = self.viewControllers.count >= itemCount ? 2 : 1;
UIViewController *popToVC = self.viewControllers[self.viewControllers.count - n];
[self popToViewController:popToVC animated:YES];
return YES;
}
// deal the gesture of return break off
- (void)dealInteractionChanges:(id<UIViewControllerTransitionCoordinatorContext>)context
{
void (^animations) (UITransitionContextViewControllerKey) = ^(UITransitionContextViewControllerKey key){
UIColor *curColor = [[context viewControllerForKey:key] wr_navBarBarTintColor];
CGFloat curAlpha = [[context viewControllerForKey:key] wr_navBarBackgroundAlpha];
[self setNeedsNavigationBarUpdateForBarTintColor:curColor];
[self setNeedsNavigationBarUpdateForBarBackgroundAlpha:curAlpha];
};
// after that, cancel the gesture of return
if ([context isCancelled] == YES)
{
double cancelDuration = [context transitionDuration] * [context percentComplete];
[UIView animateWithDuration:cancelDuration animations:^{
animations(UITransitionContextFromViewControllerKey);
}];
}
else
{
// after that, finish the gesture of return
double finishDuration = [context transitionDuration] * (1 - [context percentComplete]);
[UIView animateWithDuration:finishDuration animations:^{
animations(UITransitionContextToViewControllerKey);
}];
}
}4.5 同样，push和pop也要处理一下 ~
但是push和pop我们拿不到进度怎么办呢？处理办法是，通过交换方法，自己实现给push和pop添加进度。
// MARK: swizzling push
static CGFloat wrPushDuration = 0.10;
static int wrPushDisplayCount = 0;
- (CGFloat)wrPushProgress
{
CGFloat all = 60 * wrPushDuration;
int current = MIN(all, wrPushDisplayCount);
return current / all;
}
// swizzling system method: pushViewController
- (void)wr_pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
__block CADisplayLink *displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(pushNeedDisplay)];
[displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
[CATransaction setCompletionBlock:^{
[displayLink invalidate];
displayLink = nil;
wrPushDisplayCount = 0;
[viewController setPushToCurrentVCFinished:YES];
}];
[CATransaction setAnimationDuration:wrPushDuration];
[CATransaction begin];
[self wr_pushViewController:viewController animated:animated];
[CATransaction commit];
}计算push进度，并且根据进度更新导航栏颜色和透明度
// change navigationBar barTintColor smooth before push to current VC finished or before pop to current VC finished
- (void)pushNeedDisplay
{
if (self.topViewController != nil && self.topViewController.transitionCoordinator != nil)
{
wrPushDisplayCount += 1;
CGFloat pushProgress = [self wrPushProgress];
UIViewController *fromVC = [self.topViewController.transitionCoordinator viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toVC = [self.topViewController.transitionCoordinator viewControllerForKey:UITransitionContextToViewControllerKey];
[self updateNavigationBarWithFromVC:fromVC toVC:toVC progress:pushProgress];
}
}pop的设置方法也一样，具体请查看代码 WRNavigationBar_swift
4.6 以上都是改变导航栏的颜色和透明度，同样改变导航栏的按钮颜色和标题颜色，以及状态栏状态都和改变颜色一样，每个ViewController记录一下。需要改变的时候，ViewController 改变一下属性就ok了，非常方便！
那么接下来看一下其他demo的动态效果图吧~~~
5. 好了，来说说前面提过的自定义导航栏吧
5.1 至于怎么自定义导航栏我就不说了，来说说如果是自定义导航栏，那怎么才能像之前一样一句代码改变导航栏属性。
经过封装，自定义导航栏只需要多写一行代码！！！
// 自定义导航栏必须设置这个属性!!!!!!!
[self wr_setCustomNavBar:self.navBar];如果把这行代码放在基类控制器中，那么其他所有继承基类控制器都可以一句代码修改导航栏属性~~~
看看自定义导航栏的效果吧，是不是也很棒
6. 最后看一下移动导航栏的效果
实现代码
// 设置导航栏在垂直方向上平移多少距离
- (void)wr_setTranslationY:(CGFloat)translationY
{
// CGAffineTransformMakeTranslation 平移
self.transform = CGAffineTransformMakeTranslation(0, translationY);
}到这里就结束
