怎么在iOS中实现一个透明导航栏
这篇文章给大家介绍怎么在iOS中实现一个透明导航栏，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
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首先在需要设置导航栏透明的页面的viewDidload中写上
self.title = @"Title";
[self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
self.navigationController.navigationBar.shadowImage = [UIImage new];
self.barImageView = self.navigationController.navigationBar.subviews.firstObject;
self.barImageView.alpha = 0;
//设置状态栏
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
//设置标题颜色
self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor clearColor]};在scrollViewDidScroll代理方法中
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGFloat offset = scrollView.contentOffset.y;
//根据自己需要设置(136)的大小
CGFloat alpha = offset / 136;
_barImageView.alpha = alpha;
//记录下当前的透明度,在返回当前页面时需要
_alpha = alpha;
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithFloat:alpha] forKey:@"_alpha"];
//设置标题的透明度
self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor colorWithWhite:0 alpha:alpha]};
}当前页的viewWillAppear, viewDidAppear, viewWillDisappear
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.table.delegate = self;
}
-(void)viewDidAppear:(BOOL)animated {
BOOL isGesturePop = [[[NSUserDefaults standardUserDefaults] objectForKey:@"isGesturePop"] boolValue];
if (!isGesturePop) {
_barImageView.alpha = _alpha;
self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor colorWithWhite:0 alpha:_alpha]};
}
[super viewDidAppear:animated];
}
-(void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
self.table.delegate = nil;
self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName : [UIColor blackColor]};
_barImageView.alpha = 1;
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithBool:NO] forKey:@"isGesturePop"];
}那么在我们需要push的下一个页面需要什么操作呢,我们需要在这个页面显示正常的nav并且禁掉系统的手势pop,自己写一个pop手势,以方便我们拿到pop滑动时的偏移量,在做的时候使用了两个类,在最后会有源码贴出
B.m 须遵守UIGestureRecognizerDelegate,并导入NavigationInteractiveTransition.h
全局变量
@property (nonatomic, strong) NavigationInteractiveTransition *navT;
viewDidLoad
self.navigationController.interactivePopGestureRecognizer.enabled = NO; UIGestureRecognizer *gesture = self.navigationController.interactivePopGestureRecognizer; gesture.enabled = NO; UIView *gestureView = gesture.view; UIPanGestureRecognizer *popRecognizer = [[UIPanGestureRecognizer alloc] init]; popRecognizer.delegate = self; popRecognizer.maximumNumberOfTouches = 1; [gestureView addGestureRecognizer:popRecognizer]; _navT = [[NavigationInteractiveTransition alloc] initWithViewController:self.navigationController]; [popRecognizer addTarget:_navT action:@selector(handleControllerPop:)];
UIGestureRecognizerDelegate 代理方法gestureRecognizerShouldBegin
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
//记录当前是是否是通过手势滑动回去
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithBool:YES] forKey:@"isGesturePop"];
/**
* 这里有两个条件不允许手势执行，1、当前控制器为根控制器；2、如果这个push、pop动画正在执行（私有属性）
*/
return self.navigationController.viewControllers.count != 1 && ![[self.navigationController valueForKey:@"_isTransitioning"] boolValue];
}需要依赖的两个类源码
NavigationInteractiveTransition.h
#import@class UIViewController, UIPercentDrivenInteractiveTransition; @interface NavigationInteractiveTransition : NSObject - (instancetype)initWithViewController:(UIViewController *)vc; - (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer; - (UIPercentDrivenInteractiveTransition *)interactivePopTransition; @end
NavigationInteractiveTransition.m
#import "NavigationInteractiveTransition.h"
#import "PopAnimation.h"
@interface NavigationInteractiveTransition ()
@property (nonatomic, weak) UINavigationController *vc;
@property (nonatomic, strong) UIPercentDrivenInteractiveTransition *interactivePopTransition;
@property(nonatomic, strong) UIImageView *barImageView;
@end
@implementation NavigationInteractiveTransition
- (instancetype)initWithViewController:(UIViewController *)vc
{
self = [super init];
if (self) {
self.vc = (UINavigationController *)vc;
self.vc.delegate = self;
}
return self;
}
/**
* 我们把用户的每次Pan手势操作作为一次pop动画的执行
*/
- (void)handleControllerPop:(UIPanGestureRecognizer *)recognizer {
/**
* interactivePopTransition就是我们说的方法2返回的对象，我们需要更新它的进度来控制Pop动画的流程，我们用手指在视图中的位置与视图宽度比例作为它的进度。
*/
CGFloat progress = [recognizer translationInView:recognizer.view].x / recognizer.view.bounds.size.width;
[self.vc.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
self.vc.navigationBar.shadowImage = [UIImage new];
self.barImageView = self.vc.navigationBar.subviews.firstObject;
CGFloat alpha = [[[NSUserDefaults standardUserDefaults] objectForKey:@"_alpha"] floatValue];
self.barImageView.alpha = 1 - progress > alpha ? alpha : 1 - progress;
// NSLog(@"===progress==%.2f",progress);
/**
* 稳定进度区间，让它在0.0（未完成）～1.0（已完成）之间
*/
progress = MIN(1.0, MAX(0.0, progress));
if (recognizer.state == UIGestureRecognizerStateBegan) {
/**
* 手势开始，新建一个监控对象
*/
self.interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc] init];
/**
* 告诉控制器开始执行pop的动画
*/
[self.vc popViewControllerAnimated:YES];
}
else if (recognizer.state == UIGestureRecognizerStateChanged) {
/**
* 更新手势的完成进度
*/
[self.interactivePopTransition updateInteractiveTransition:progress];
}
else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled) {
/**
* 手势结束时如果进度大于一半，那么就完成pop操作，否则重新来过。
*/
if (progress > 0.5) {
[self.interactivePopTransition finishInteractiveTransition];
self.barImageView.alpha = 0;;
}
else {
[self.interactivePopTransition cancelInteractiveTransition];
}
self.interactivePopTransition = nil;
}
}
- (id)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC {
/**
* 方法1中判断如果当前执行的是Pop操作，就返回我们自定义的Pop动画对象。
*/
if (operation == UINavigationControllerOperationPop)
return [[PopAnimation alloc] init];
return nil;
}
- (id)navigationController:(UINavigationController *)navigationController
interactionControllerForAnimationController:(id)animationController {
/**
* 方法2会传给你当前的动画对象animationController，判断如果是我们自定义的Pop动画对象，那么就返回interactivePopTransition来监控动画完成度。
*/
if ([animationController isKindOfClass:[PopAnimation class]])
return self.interactivePopTransition;
return nil;
}
@end PopAnimation.h
#import#import @interface PopAnimation : NSObject @end
PopAnimation.m
#import "PopAnimation.h" @interface PopAnimation () @property (nonatomic, strong) idtransitionContext; @end @implementation PopAnimation - (NSTimeInterval)transitionDuration:(id )transitionContext { //这个方法返回动画执行的时间 return 0.25; } /** * transitionContext你可以看作是一个工具，用来获取一系列动画执行相关的对象，并且通知系统动画是否完成等功能。 */ - (void)animateTransition:(id )transitionContext { /** * 获取动画来自的那个控制器 */ UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; /** * 获取转场到的那个控制器 */ UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; /** * 转场动画是两个控制器视图时间的动画，需要一个containerView来作为一个“舞台”，让动画执行。 */ UIView *containerView = [transitionContext containerView]; [containerView insertSubview:toViewController.view belowSubview:fromViewController.view]; NSTimeInterval duration = [self transitionDuration:transitionContext]; /** * 执行动画，我们让fromVC的视图移动到屏幕最右侧 */ [UIView animateWithDuration:duration animations:^{ fromViewController.view.transform = CGAffineTransformMakeTranslation([UIScreen mainScreen].bounds.size.width, 0); }completion:^(BOOL finished) { /** * 当你的动画执行完成，这个方法必须要调用，否则系统会认为你的其余任何操作都在动画执行过程中。 */ [transitionContext completeTransition:!transitionContext.transitionWasCancelled]; }]; } - (void)animationDidStop:(CATransition *)anim finished:(BOOL)flag { [_transitionContext completeTransition:!_transitionContext.transitionWasCancelled]; } @end
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