iOS navigationBar设置透明无效果

Question

This is my code:

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:[UIImage new]];
}

but navigationBar is still gray, Why?

In a new project this code is ok.

Answer 1

I have changed color using following code.

self.navigationController.navigationBar.barTintColor =  [UIColor colorWithPatternImage:[UIImage imageNamed:@"greenPatter.png"]];

    CGRect bgFrame = self.navigationController.navigationBar.bounds;

    bgFrame.origin.y -= 20.0;

    bgFrame.size.height += 20.0;

    UIView *backgroundView = [[UIView alloc] initWithFrame:bgFrame];

    backgroundView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    backgroundView.backgroundColor =  [UIColor colorWithPatternImage:[UIImage imageNamed:@"greenPatter.png"]];

    backgroundView.alpha = 0.6;

    [self.navigationController.navigationBar addSubview:backgroundView];

 [self.navigationController.navigationBar sendSubviewToBack:backgroundView];

    [self.navigationController.navigationBar setTitleTextAttributes:
     @{NSForegroundColorAttributeName:[UIColor whiteColor]}];

greenPatter.png is image of greencolor, You can also replace

self.navigationController.navigationBar.barTintColor =  [UIColor colorWithPatternImage:[UIImage imageNamed:@"greenPatter.png"]];

to

self.navigationController.navigationBar.barTintColor =  [UIColor clearColor];

It's working for me. Try and Let me know.

Answer 2

我可能会说清楚，但您尝试过吗？

    [self.navigationController.navigationBar setBackgroundColor:[UIColor clearColor]];

Answer 3

The following code do well.

UINavigationBar *bar =  [UINavigationBar appearance];
[bar setBackgroundImage:[UIImage imageNamed:@"navbg"] forBarMetrics:UIBarMetricsDefault];

Answer 4

To set transparent I use this code

- (void)viewWillAppear:(BOOL)animated {

    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.shadowImage = [[UIImage alloc] init];
    self.navigationController.navigationBar.barTintColor = [UIColor clearColor];

    [super viewWillAppear:animated];
}

Then to get color back

- (void)viewWillDisappear:(BOOL)animated {


    [self.navigationController.navigationBar setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.shadowImage = nil;
    self.navigationController.navigationBar.barTintColor = [UIColor redColor];


    [super viewWillDisappear:animated];
}

Answer 5

Use this code in AppDelegate.m class

[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"topbar-bg"] forBarMetrics:UIBarMetricsDefault];

Answer 6

A fully transparent navigation bar:

- (void)transparentNavigationBar {

    UINavigationBar *navBarAppearance = [UINavigationBar appearance];

    [navBarAppearance setBackgroundImage:[UIImage new]
                                                  forBarMetrics:UIBarMetricsDefault];
    [navBarAppearance setShadowImage:[UIImage new]];
    [navBarAppearance setTranslucent:YES];

}

If you want to make it semi-transparent set translucent to NO and set desired batTintColor with alpha < 1.