TabBar 选择指示器图像在 Objective C 中没有占据 tabBar 高度的整个大小答案

【问题标题】：UITabBar selection indicator image is not taking whole size of tabBar height in ObjectiveCTabBar 选择指示器图像在 Objective C 中没有占据 tabBar 高度的整个大小
【发布时间】：2014-10-31 13:28:38
【问题描述】：

我正在更改 setSelectionIndicatorImage，当我在 iOS 8 上运行应用程序时，图像和常规宽度之间的间距为 tabBar。有没有办法可以将标签栏的高度与setSelectionIndicatorImage 匹配？ Also I get margin of few pixels on left side of first tab and right side of last tab, and I need to cover that with image too when tab is selected.

【问题讨论】：

请添加修改过的和想要的图片。同时添加您的代码。
还可以查看本教程。这可能会有所帮助。 blog.erikvdwal.nl/customizing-the-uitabbar-in-ios-5-and-ios-6
请参考选择/取消选择标签栏图像的正确图像尺寸。 developer.apple.com/library/ios/documentation/UserExperience/…
您是否能够删除第一个选项卡左侧和最后一个选项卡右侧的几个像素边距？

标签： ios objective-c uitabbar uitabbaritem

【解决方案1】：

在 didFinishLaunchingWithOptions 上放这个代码：

UITabBarController *tabBarContr = (UITabBarController *)self.window.rootViewController;

CGFloat tabBarItemWidth = self.window.rootViewController.view.bounds.size.width / tabBarContr.tabBar.items.count;
CGFloat tabBarItemHeight = CGRectGetHeight(tabBarContr.tabBar.frame);

UIView *selectedBottomView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, tabBarItemWidth, tabBarItemHeight)];

 CAGradientLayer *gradient = [CAGradientLayer layer];

gradient.colors = [NSArray arrayWithObjects:
                   (id)[UIColor blueButton].CGColor,
                   (id)[UIColor colorWithRed:0.08 green:0.54 blue:1 alpha:1].CGColor,
                   nil];

gradient.frame = selectedBottomView.bounds;

[selectedBottomView.layer insertSublayer:gradient atIndex:0];

UIGraphicsBeginImageContext(selectedBottomView.bounds.size);
[selectedBottomView.layer renderInContext:UIGraphicsGetCurrentContext()];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

tabBarContr.tabBar.selectionIndicatorImage = image;
tabBarContr.tabBar.translucent = YES;
tabBarContr.tabBar.tintColor = [UIColor whiteColor];

注意：以imageview代替渐变

【讨论】：

【解决方案2】：

这应该可以帮助您根据需要自定义指示器图像。您只是在界面构建器中将 Tab Bar 的类设置为此类

class MyCustomTabBar: UITabBar
{
    var didInit = false
    override func layoutSubviews()
    {
        super.layoutSubviews()

        if didInit == false
        {
            didInit = true
            for subview in subviews {
                // can't hookup to subviews, so do layer.sublayers
                subview.layer.addObserver(self, forKeyPath: "sublayers", options: .New, context: nil)
            }
        }
    }

    deinit
    {
        for subview in subviews
        {
            subview.layer.removeObserver(self, forKeyPath: "sublayers")
        }
    }

    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>)
    {
        // layer.delegate is usually the parent view
        if let l = object as? CALayer, tbButton = l.delegate as? UIView where tbButton.window != nil
        {
            for v in tbButton.subviews
            {
                if String(v.dynamicType) == "UITabBarSelectionIndicatorView" {
                    // do whatever needed with v, this is your indicator view
                }
            }
        }
    }
}

【讨论】：