【iOS】关于keyWindow的获取

iOS13之前的获取方式

UIApplication.sharedApplication.keyWindow

iOS13 之后新增了UIWindowScene，keyWindow的获取也有了新的方式，将来肯定会移除该字段，记录下方法提前适配。

@property(nullable, nonatomic,readonly) UIWindow *keyWindow 
API_DEPRECATED("Should not be used for applications that support multiple scenes as it returns a key window across all connected scenes", ios(2.0, 13.0));

直接上代码

+ (UIWindow *)zyl_keyWindow
{
    if (@available(iOS 13.0, *)) {
        for (UIWindowScene *windowScene in UIApplication.sharedApplication.connectedScenes) {
            if (windowScene.activationState == UISceneActivationStateForegroundActive) {
                for (UIWindow *window in windowScene.windows) {
                    if (window.isKeyWindow) {
                        return window;
                    }
                }
                break;
            }
        }
    } else {
        return UIApplication.sharedApplication.keyWindow;
    }
    
    return nil;
}

也有使用以下方式的

UIApplication.sharedApplication.delegate.window

但是现在新建项目 UIApplication 里不会创建 window，需要手动创建 window属性。SceneDelegate里也要加上window属性，否则调用会崩溃。