iOS - 实现导航栏透明的几种方法(总结)

前言:

在开发中,为了美观很多设计成导航栏透明的样式,下面就列举一下实现导航栏透明的几种方法

第一种方法:

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    for (UIView *aView in self.navigationController.navigationBar.subviews) {
        
        if ([aView isKindOfClass:NSClassFromString(@"_UINavigationBarBackground")]) {
            
            aView.hidden = YES;
            
        }
    }
    
}
- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    for (UIView *aView in self.navigationController.navigationBar.subviews) {
        
        if ([aView isKindOfClass:NSClassFromString(@"_UINavigationBarBackground")]) {
            aView.hidden = NO;
        }
        
    }
    
}

第二种方法:

[self.navigationController.navigationBar setBackgroundImage:[UIImage new] forBarMetrics:UIBarMetricsDefault];
    //去除 navigationBar 底部的细线
    self.navigationController.navigationBar.shadowImage = [UIImage new];

第三种方法

self.navigationController.navigationBar.shadowImage = [[UIImage alloc] init];
    UIImage *image = [self createAImageWithColor:[UIColor clearColor] alpha:0.0];
    [self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];

- (UIImage *)createAImageWithColor:(UIColor *)color alpha:(CGFloat)alpha{
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextSetAlpha(context, alpha);
    CGContextFillRect(context, rect);
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return theImage;
}

注意点:

设置导航栏透明的时候,如果在Push到其他的控制器,其他的控制器导航栏也是会变得透明,所以为了防止这类情况的发生,最好在- (void)viewWillDisappear:(BOOL)animated方法中,把导航栏的颜色还原过来