【移动应用开发技术】怎么在iOS中实现一个透明导航栏

【移动应用开发技术】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。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;viewDidLoadself.navigationCeractivePopGestureRecognizer.enabled

=

NO;

UIGestureRecognizer

*gesture

=

self.navigationCeractivePopGestureRecognizer;

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

<UIKit/UIKit.h>

@class

UIViewController,

UIPercentDrivenInteractiveTransition;

@interface

NavigationInteractiveTransition

:

NSObject

<UINavigationControllerDelegate>

-

(instancetype)initWithViewController:(UIViewController

*)vc;

-

(void)handleControllerPop:(UIPanGestureRecognizer

*)recognizer;

-

(UIPercentDrivenInteractiveTransition

*)interactivePopTransition;

@endNavigationInteractiveTransition.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

*/

eractivePopTransition

=

[[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

*/

[eractivePopTransition

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)

{

[eractivePopTransition

finishInteractiveTransition];

self.barImageView.alpha

=

0;;

}

else

{

[eractivePopTransition

cancelInteractiveTransition];

}

eractivePopTransition

=

nil;

}

}

-

(id<UIViewControllerAnimatedTransitioning>)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<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController

*)navigationController

interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)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

eractivePopTransition;

return

nil;

}

@endPopAnimation.h#import

<Foundation/Foundation.h>

#import

<UIKit/UIKit.h>

@interface

PopAnimation

:

NSObject

<UIViewControllerAnimatedTransitioning>

@endPopAnimation.m#import

"PopAnimation.h"

@interface

PopAnimation

()

@property

(nonatomic,

strong)

id

<UIViewControllerContextTransitioning>

transitionContext;

@end

@implementation

PopAnimation

-

(NSTimeInterval)transitionDuration:(id

<UIViewControllerContextTransitioning>)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

<UIViewControllerContextTransitioning>)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contain