iOS 动态修改导航栏颜色 UINavigationBar

示例

所谓动态修改意思是在当前页面滚动的过程中亦或是在触发返回事件\进入一个新的页面导航栏的动态变化

由于系统级别的navBar 高度集成很多自己想实现的功能很不好弄如果是通过继承的话, 参见 category 类别那章相对来说更适用,自己开发一些个性自定义的方法去实现想要的功能.

参见http://www.cocoachina.com/ios/20150409/11505.html

这篇文章就是用类别的方法拓展了 navigationBar 的实例方法 . 甚至动用了 c 底层. 不过使用起来还是很方便

上关键类别代码

//

//  UINavigationBar+MyNavBar.h

//  LTNavigationBar

#import <UIKit/UIKit.h>

 @interface UINavigationBar (MyNavBar)

- (void)lt_setBackgroundColor:(UIColor *)backgroundColor;

- (void)lt_setElementsAlpha:(CGFloat)alpha;

- (void)lt_setTranslationY:(CGFloat)translationY;

- (void)lt_reset;

@end

//

//  UINavigationBar+Awesome.m

//  LTNavigationBar

#import "UINavigationBar+MyNavBar.h"

#import <objc/runtime.h>

@implementation UINavigationBar (MyNavBar)

static char overlayKey;

- (UIView *)overlay

{

    return objc_getAssociatedObject(self, &overlayKey);

}

- (void)setOverlay:(UIView *)overlay

{

    objc_setAssociatedObject(self, &overlayKey, overlay, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

}

- (void)lt_setBackgroundColor:(UIColor *)backgroundColor

{

    if (!self.overlay) {

        [self setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];

        self.overlay = [[UIView alloc] initWithFrame:CGRectMake(, -, [UIScreen mainScreen].bounds.size.width, CGRectGetHeight(self.bounds) + )];

        self.overlay.userInteractionEnabled = NO;

        self.overlay.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;

        [self insertSubview:self.overlay atIndex:];

    }

    self.overlay.backgroundColor = backgroundColor;

}

- (void)lt_setTranslationY:(CGFloat)translationY

{

    self.transform = CGAffineTransformMakeTranslation(, 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;

            *stop = YES;

        }

    }];

}

- (void)lt_reset

{

    [self setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];

    [self.overlay removeFromSuperview];

    self.overlay = nil;

}

@end

调用示例这个效果透明度的更改也是仿淘宝展示具体商品页面的滑动效果可以去查看

- (void)viewDidLoad {

    [super viewDidLoad];

    self.tableView.dataSource = self;

    [self.navigationController.navigationBar lt_setBackgroundColor:[UIColor clearColor]];
    [self setBackButtonStyleLight:YES];

}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    UIColor * color = [UIColor colorWithRed:/255.0 green:/255.0 blue:/255.0 alpha:];

    CGFloat offsetY = scrollView.contentOffset.y;

    if (offsetY > NAVBAR_CHANGE_POINT) {

        CGFloat alpha = MIN(,  - ((NAVBAR_CHANGE_POINT +  - offsetY) / )); // NAVBAR_CHANGE_POINT  和  64  这两个参数 都是 看效果需求可酌情更改  就是 透明度变化的时机 系数

        [self.navigationController.navigationBar lt_setBackgroundColor:[color colorWithAlphaComponent:alpha]];

[self setBackButtonStyleLight:NO alpha:alpha];

    } else {

        [self.navigationController.navigationBar lt_setBackgroundColor:[color colorWithAlphaComponent:]];

[self setTitle:@""];

[self setBackButtonStyleLight:YES];

    }

}

- (void)setBackButtonStyleLight:(BOOL)isLight

{

    [self setBackButtonStyleLight:isLight alpha:];

}

- (void)setBackButtonStyleLight:(BOOL)isLight alpha:(CGFloat)alpha

{

    if(isLight){

        [titleLabel setAlpha:];//导航标题

        [backButton setAlpha:];//返回按钮

        [titleLabel setText:@""];

        UIImage *image = backButton.imageView.image;

        UIImage *targetImage = [UIImage imageNamed:@"icon_fanhi"];

        if(image != targetImage){

            [backButton setImage:[UIImage imageNamed:@"icon_fanhi"] forState:UIControlStateNormal];

            [backButton setImage:[UIImage imageNamed:@"icon_fanhi"] forState:UIControlStateHighlighted];

        }

    }else{

        if(alpha < 0.5){

            [titleLabel setText:@""];

            UIImage *image = backButton.imageView.image;

            UIImage *targetImage = [UIImage imageNamed:@"icon_fanhi"];

            if(image != targetImage){

                [backButton setImage:[UIImage imageNamed:@"icon_fanhi"] forState:UIControlStateNormal];

                [backButton setImage:[UIImage imageNamed:@"icon_fanhi"] forState:UIControlStateHighlighted];

            }

            //先是之前的消失

            [backButton setAlpha:(0.5 - alpha) * ];

        }else{

            UIImage *image = backButton.imageView.image;

            UIImage *targetImage = [UIImage imageNamed:@"icon_fanhihei"];

            if(image != targetImage){

                [backButton setImage:[UIImage imageNamed:@"icon_fanhihei"] forState:UIControlStateNormal];

                [backButton setImage:[UIImage imageNamed:@"icon_fanhihei"] forState:UIControlStateHighlighted];

            }

            [titleLabel setText:foodItemModel.foodName];

            //将返回和分享慢慢出现

            CGFloat showAlpha = (alpha - 0.5) * ;

            [titleLabel setAlpha:showAlpha];

            [backButton setAlpha:showAlpha];

        }

    }

}

- (void)viewWillAppear:(BOOL)animated

{

    [super viewWillAppear:YES];

    [self initScrollNav];

}

- (void)viewWillDisappear:(BOOL)animated

{

    [super viewWillDisappear:animated];

    //self.tableView.delegate = nil;//废弃代码

    [self.navigationController.navigationBar lt_reset];//页面消失时候要 恢复 正常导航栏模式

}

- (void)initScrollNav

{

    self.tableView.delegate = self;

    [self scrollViewDidScroll:self.tableView];

    [self.tableView reloadData];

    [self.navigationController.navigationBar setShadowImage:[UIImage new]];

}

- (void)dealloc

{

    self.tableView.delegate = nil;//不能在 viewWilldisappear 里nil 这时候 仍然会触发 scrollViewDidLoad 导致崩溃 需要卸写在这里

}

还有一种情况就是滚动过程中导航栏消失保留状态栏这种情况一些产品比较青睐我个人特别不喜欢一直坚信 ios7以后苹果就是倡导状态栏导航栏一体化所以留个状态栏你以为是安卓吗? 丑爆了然并卵开发者只有提建议的权利没有决定权怎么实现还是要会的是吧

示例:

- (void)viewDidLoad {

    [super viewDidLoad];

    self.tableView.delegate = self;

    self.tableView.dataSource = self;

    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"Cell"];

}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    CGFloat offsetY = scrollView.contentOffset.y;

    if (offsetY > ) {

        if (offsetY >= ) {

            [self setNavigationBarTransformProgress:];

        } else {

            [self setNavigationBarTransformProgress:(offsetY / )];

        }

    } else {

        [self setNavigationBarTransformProgress:];

        self.navigationController.navigationBar.backIndicatorImage = [UIImage new];

    }

}

- (void)setNavigationBarTransformProgress:(CGFloat)progress

{

    [self.navigationController.navigationBar lt_setTranslationY:(- * progress)];

    [self.navigationController.navigationBar lt_setElementsAlpha:(-progress)];

}

- (void)viewWillAppear:(BOOL)animated

{

    [super viewWillAppear:YES];//保留状态栏的那种情况

}

- (void)viewWillDisappear:(BOOL)animated

{

    [super viewWillDisappear:animated];

    [self.navigationController.navigationBar lt_reset];

}

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iOS 动态修改导航栏颜色 UINavigationBar

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