Xamarin.Forms 上的部分安全区域

Question

我有一个包含需要安全区域填充的 ListView 的页面，以便 iPhone X 凸块不会在横向方向上剪切 ListView 内容。但是，ListView 的底部不需要填充；屏幕的圆底角不会干扰。

页面通过从构造函数调用这个来启用安全区域填充：

Xamarin.Forms.PlatformConfiguration.iOSSpecific.Page.SetUseSafeArea(On<Xamarin.Forms.PlatformConfiguration.iOS>(), true);

如何为除底部之外的所有侧面保留安全区域填充？即使用户在使用页面时旋转屏幕方向，该解决方案也必须有效。

Answer 1

可以通过使用Xamarin.Forms.PlatformConfiguration.iOSSpecific 命名空间中的Page.SafeAreaInsets 方法检索其Thickness 值来自定义安全区域。然后可以根据需要进行修改并重新分配给页面构造函数中的 Padding 属性或OnAppearing override：

protected override void OnAppearing()
{
    base.OnAppearing();

    var safeInsets = On<iOS>().SafeAreaInsets();
    safeInsets.Bottom = 0;
    safeInsets.Top = 35;
    safeInsets.Left = 35;
    safeInsets.Right = 35;
    Padding = safeInsets;
}

人像的效果：

风景的效果：

如果需要在设备方向改变时自定义SafeAreaInsets。有一个OnSizeAllocated的方法可以很方便的使用。

protected override void OnSizeAllocated(double width, double height)
{
    base.OnSizeAllocated(width, height);
    if (width != this.width || height != this.height)
    {
        this.width = width;
        this.height = height;
        if (width > height)
        {
            Console.WriteLine("Landscape");
            var safeInsets = On<iOS>().SafeAreaInsets();
            safeInsets.Bottom = 0;
            safeInsets.Top = 0;
            safeInsets.Left = 35;
            safeInsets.Right = 35;
            Padding = safeInsets;
        }
        else
        {
            Console.WriteLine("Portrait");
            var safeInsets = On<iOS>().SafeAreaInsets();
            safeInsets.Bottom = 0;
            safeInsets.Top = 35;
            safeInsets.Left = 0;
            safeInsets.Right = 0;
            Padding = safeInsets;
        }
    }
}

==================================更新============= ====================

如果需要适配越来越多的设备，可以通过一些手机型号判断（比如iPhone X）来设置两侧安全区域的大小。另外，还可以查看是否包含Navigation Bar或 Tab Bar 修改 Thickness 的大小。应该是

protected override void OnSizeAllocated(double width, double height)
{
    base.OnSizeAllocated(width, height);
    if (width != this.width || height != this.height)
    {
        this.width = width;
        this.height = height;
        if (width > height)
        {
            Console.WriteLine("Landscape");
            var safeInsets = On<iOS>().SafeAreaInsets();
            // whether is iPhone X
            if (deveiceType.Equals("iPhone X"))
            {
                //whether contain Navigation Bar
                if (ContainNavigationBar) { safeInsets.Top = 44; } else { safeInsets.Top = 0; }
                //whether conatin Tab Bar
                if (ContainTabBar) { safeInsets.Bottom = 34; } else { safeInsets.Bottom = 0; }
            }
            safeInsets.Left = 35;
            safeInsets.Right = 35;
            Padding = safeInsets;
            Padding = safeInsets;
        }
        else
        {
            Console.WriteLine("Portrait");
            var safeInsets = On<iOS>().SafeAreaInsets();
            // whether is iPhone X
            if (deveiceType.Equals("iPhone X"))
            {
                //whether contain Navigation Bar
                if (ContainNavigationBar) { safeInsets.Top = 84; } else { safeInsets.Top = 44; }
                //whether conatin Tab Bar
                if (ContainTabBar) { safeInsets.Bottom = 34; }else{ safeInsets.Bottom = 0; }
            }
            safeInsets.Left = 0;
            safeInsets.Right = 0;
            Padding = safeInsets;
        }
    }
}

只要苹果以后不改变状态栏的高度，我认为硬编码设置的高度不会有问题。