如何正确设置导航栏透明度

2017-01-04

需求

很多时候，希望导航栏能够透明，同时item不透明，看了网上的做法，参测不齐。这里作为过来人~~自己走过的坑~~有必要说说。

需求一：希望导航栏一直透明，且item也透明

1	[self.navigationController setNavigationBarHidden:YES animated:NO];

需求二：希望导航栏一直透明，item不透明

- (void)viewDidLoad {
    [super viewDidLoad];
    self.edgesForExtendedLayout = UIRectEdgeAll;
    self.automaticallyAdjustsScrollViewInsets = NO;
}
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.shadowImage = [UIImage new];
    self.navigationController.navigationBar.translucent = YES;
}
- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self.navigationController.navigationBar setBackgroundImage:[UIImage imageWithColor:RGBACOLOR(56.0, 25.0, 114.0, 1.0)] forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.shadowImage = [UIImage imageWithColor:RGBACOLOR(56.0, 25.0, 114.0, 1.0)];
    self.navigationController.navigationBar.translucent = NO;
}

需求三：希望导航栏随着UIScrollView/UITableView滑动变化颜色，且item不透明

效果图

这里需要借助第三方LTNavigationBar

#import "UINavigationBar+Awesome.h"
- (void)viewDidLoad {
    [super viewDidLoad];
    self.edgesForExtendedLayout = UIRectEdgeAll;
    self.automaticallyAdjustsScrollViewInsets = NO;
}
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.shadowImage = [UIImage new];
    self.navigationController.navigationBar.translucent = YES;
}
- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self.navigationController.navigationBar lt_reset];
}
- (void)setNavigationColor:(CGFloat)contentOffSet_y {
    if (contentOffSet_y >= -10.0) {
        if (contentOffSet_y <= 0) {
            [self.navigationController.navigationBar lt_setBackgroundColor:RGBACOLOR(56.0, 25.0, 114.0, 0.0)];
        }
        if (contentOffSet_y >= 0) {
            if (contentOffSet_y <= 130.0) {
                [self.navigationController.navigationBar lt_setBackgroundColor:RGBACOLOR(56.0, 25.0, 114.0, 1.0 / 130.0 * contentOffSet_y)];
            } else {
                [self.navigationController.navigationBar lt_setBackgroundColor:RGBACOLOR(56.0, 25.0, 114.0, 1.0)];
            }
        }
    }
    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    [self setNavigationColor:scrollView.contentOffset.y];
}

再一次感谢您花费时间阅读这篇文章！

微博： @Danny_吕昌辉
博客： SuperDanny