ios 导航栏透明， 上下滑动 导航栏 颜色渐变

 

- (void)viewWillAppear:(BOOL)animated {

//设置导航栏背景图片为一个空的image，这样就透明了

    [self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsCompact];

    //去掉透明后导航栏下边的黑边

//    [self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];

    self.navigationController.navigationBar.translucent = YES;//这个必须设置

 

}

 

 

- (void)viewWillDisappear:(BOOL)animated {

    // 返回时不让其他页面的导航栏变为透明 需要重置

    [self.navigationController.navigationBar setBackgroundImage:nil forBarMetrics:UIBarMetricsCompact];

//    [self.navigationController.navigationBar setShadowImage:nil];

    self.navigationController.navigationBar.translucent = NO;

}

 

 

//如果要监听滚动而使导航栏颜色渐变，在scrollView的代理方法中添加代码

 

-(void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    //滑动渐变颜色

    [self.navigationController.navigationBar setBackgroundImage:[self imageWithBgColor:[UIColor colorWithRed:18/255.0 green:151/255.0 blue:171/255.0 alpha:self.myTableView.contentOffset.y /100]] forBarMetrics:UIBarMetricsDefault];// 颜色自己设置 渐变开始的位置自己算

    

}

 

-(UIImage *)imageWithBgColor:(UIColor *)color {

    

    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);

    

    UIGraphicsBeginImageContext(rect.size);

    

    CGContextRef context = UIGraphicsGetCurrentContext();

    

    CGContextSetFillColorWithColor(context, [color CGColor]);

    

    CGContextFillRect(context, rect);

    

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    

    UIGraphicsEndImageContext();

    

    return image;

}

 

 

 

/*------------导航栏常用属性--------*/

 

1. 导航栏背景色设置:

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

2. 导航栏标题颜色字体大小

       NSMutableDictionary *attrs = [NSMutableDictionary dictionary];

       attrs[NSForegroundColorAttributeName] = [UIColor whiteColor];

       attrs[NSFontAttributeName] = [UIFont systemFontOfSize:17];

       [self.navigationController.navigationBar setTitleTextAttributes:attrs];

3. 导航栏左右item

    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithTitle:@"left" style:UIBarButtonItemStylePlain target:self action:@selector(left)];

     self.navigationItem.leftBarButtonItem = leftItem;

     UIBarButtonItem *rightItem = [[UIBarButtonItem alloc] initWithTitle:@"right" style:UIBarButtonItemStylePlain target:self action:@selector(right)];   

       self.navigationItem.rightBarButtonItem = rightItem;

4. 导航栏item字体颜色

    self.navigationController.navigationBar.tintColor = [UIColor redColor];如果要不同item不同颜色，那么item要带一个自定义按钮，在设置按钮属性

5. 当前控制器的下一个控制器的返回item去掉文字只保留箭头

       UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:self action:@selector(back)];

    self.navigationItem.backBarButtonItem = backItem;