C# 如何以编程方式为iOS正确地将UI元素添加到视图中?
我正在使用Visual Studio 2013中的Xamarin.iOS以编程方式在C#中构建一个简单的用户界面。我知道使用designer视图要容易得多,但它现在对我不起作用 到目前为止,我已经设法让MPMoviePlayerController和TextView显示,但TextView不会滚动,尽管我添加了这样做的要求 文本视图与视频重叠,因为我可以听到背景中播放的音频。而UILabel在哪里也看不见 我认为添加每个UI元素作为主视图的子视图,将以堆栈顺序显示元素,在顶部显示视频,在视频和文本视图的右下方添加标签并滚动 在某种程度上,我想让它们一层一层地堆叠在一起。什么是我做得不对或者我遗漏了什么C# 如何以编程方式为iOS正确地将UI元素添加到视图中?,c#,ios,uiview,xamarin,xamarin.ios,C#,Ios,Uiview,Xamarin,Xamarin.ios,我正在使用Visual Studio 2013中的Xamarin.iOS以编程方式在C#中构建一个简单的用户界面。我知道使用designer视图要容易得多,但它现在对我不起作用 到目前为止,我已经设法让MPMoviePlayerController和TextView显示,但TextView不会滚动,尽管我添加了这样做的要求 文本视图与视频重叠,因为我可以听到背景中播放的音频。而UILabel在哪里也看不见 我认为添加每个UI元素作为主视图的子视图,将以堆栈顺序显示元素,在顶部显示视频,在视频和文
using System;
using System.Drawing;
using Foundation;
using UIKit;
using MediaPlayer;
public partial class VideoViewController : UIViewController
{
MPMoviePlayerController moviePlayer;
UILabel label;
UITextView textView;
public VideoViewController() : base("VideoViewController", null)
{
}
public override void DidReceiveMemoryWarning()
{
// Releases the view if it doesn't have a superview.
base.DidReceiveMemoryWarning();
// Release any cached data, images, etc that aren't in use.
}
public override void ViewDidLoad()
{
base.ViewDidLoad();
// Perform any additional setup after loading the view, typically from a nib.
moviePlayer = new MPMoviePlayerController(NSUrl.FromString("http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4")); // Use FromString() to play video directly from web.
moviePlayer.View.Frame = new CoreGraphics.CGRect(0, 20, this.View.Frame.Size.Width, 180); // size of the video frame
moviePlayer.ScalingMode = MPMovieScalingMode.AspectFit; // show the video relative to the video size dimensions
moviePlayer.PrepareToPlay();
moviePlayer.Play();
this.View.AddSubview(moviePlayer.View); // add the view after video starts playing to display it
// UILabel
label = new UILabel();
label.Text = "Tutorial";
label.Font.WithSize(36);
this.View.AddSubview(label.ViewForBaselineLayout);
// UITextView
textView = new UITextView();
textView.Editable = false;
textView.ScrollEnabled = true;
textView.UserInteractionEnabled = true;
textView.ViewForBaselineLayout.Frame = new CoreGraphics.CGRect(0, 0, this.View.Frame.Size.Width, this.View.Frame.Size.Height*3);
textView.Text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. [shorten text for this post] "; // shorten text for this post
this.View.AddSubview(textView);
}
}
}
我猜你希望它是这样的:
using System;
using System.Drawing;
using Foundation;
using UIKit;
using MediaPlayer;
using CoreGraphics;
namespace CHANGE_THIS_TO_YOUR_NAME_SPACE
{
public partial class VideoViewController : UIViewController
{
MPMoviePlayerController moviePlayer;
UILabel label;
UITextView textView;
public VideoViewController () : base ("VideoViewController", null)
{
}
public override void DidReceiveMemoryWarning ()
{
// Releases the view if it doesn't have a superview.
base.DidReceiveMemoryWarning ();
// Release any cached data, images, etc that aren't in use.
}
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
// Perform any additional setup after loading the view, typically from a nib.
moviePlayer = new MPMoviePlayerController (NSUrl.FromString ("http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4")); // Use FromString() to play video directly from web.
moviePlayer.View.Frame = new CGRect (0, 20, View.Frame.Size.Width, 180); // size of the video frame
moviePlayer.ScalingMode = MPMovieScalingMode.AspectFit; // show the video relative to the video size dimensions
moviePlayer.PrepareToPlay ();
moviePlayer.Play ();
View.Add (moviePlayer.View); // add the view after video starts playing to display it
// UILabel
label = new UILabel (new CGRect(0,200, View.Frame.Size.Width, 50));
label.Text = "Tutorial";
label.Font.WithSize (36);
View.Add (label.ViewForBaselineLayout);
// UITextView
textView = new UITextView ();
textView.Editable = false;
textView.ScrollEnabled = true;
textView.UserInteractionEnabled = true;
textView.ViewForBaselineLayout.Frame = new CGRect (0, 250, View.Frame.Size.Width, View.Frame.Size.Height * 3);
textView.Text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. [shorten text for this post] "; // shorten text for this post
View.Add (textView);
}
}
}
基本上,当您使用CGRect
itsnewcgrect(x-coord,y-coord,width,height)
设置视图的框架时,您就快到了。由于所有视图均为0,0,因此它们被放置在彼此的顶部。另外,UITextView
也不会滚动,因为它的高度是屏幕高度的三倍。如果要滚动内容(文本),则需要将其延伸到框架之外
引入iOS9UIStackView
请参阅WWDC 2015的视频:但如果您支持iOS7/8,则有一些第三方实现。Forms有一个stacklayout,所以这可能也是一个选项
改进的解决方案是不设置视图的框架,而是使用自动布局约束,如下所示:
using System;
using System.Drawing;
using Foundation;
using UIKit;
using MediaPlayer;
using CoreGraphics;
namespace CHANGE_THIS_TO_YOUR_NAME_SPACE
{
public partial class VideoViewController : UIViewController
{
MPMoviePlayerController moviePlayer;
UILabel label;
UITextView textView;
public VideoViewController () : base ("VideoViewController", null)
{
}
public override void DidReceiveMemoryWarning ()
{
// Releases the view if it doesn't have a superview.
base.DidReceiveMemoryWarning ();
// Release any cached data, images, etc that aren't in use.
}
public override void ViewDidLoad ()
{
base.ViewDidLoad ();
// Perform any additional setup after loading the view, typically from a nib.
moviePlayer = new MPMoviePlayerController (NSUrl.FromString ("http://clips.vorwaerts-gmbh.de/big_buck_bunny.mp4")); // Use FromString() to play video directly from web.
moviePlayer.View.TranslatesAutoresizingMaskIntoConstraints = false;
// moviePlayer.View.Frame = new CGRect (0, 20, View.Frame.Size.Width, 180); // size of the video frame
moviePlayer.ScalingMode = MPMovieScalingMode.AspectFit; // show the video relative to the video size dimensions
moviePlayer.PrepareToPlay ();
moviePlayer.Play ();
View.Add (moviePlayer.View); // add the view after video starts playing to display it
// UILabel
// label = new UILabel (new CGRect(0,200, View.Frame.Size.Width, 50));
label = new UILabel ();
label.TranslatesAutoresizingMaskIntoConstraints = false;
label.Text = "Tutorial";
label.Font.WithSize (36);
View.Add (label.ViewForBaselineLayout);
// UITextView
textView = new UITextView ();
textView.TranslatesAutoresizingMaskIntoConstraints = false;
textView.Editable = false;
textView.ScrollEnabled = true;
textView.UserInteractionEnabled = true;
// textView.ViewForBaselineLayout.Frame = new CGRect (0, 250, View.Frame.Size.Width, View.Frame.Size.Height * 3);
textView.Text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. [shorten text for this post] "; // shorten text for this post
View.Add (textView);
SetUpAutoLayoutConstraints ();
}
private void SetUpAutoLayoutConstraints()
{
View.AddConstraints (new [] {
NSLayoutConstraint.Create(moviePlayer.View, NSLayoutAttribute.Width, NSLayoutRelation.Equal, View, NSLayoutAttribute.Width, 1, 0),
NSLayoutConstraint.Create(moviePlayer.View, NSLayoutAttribute.Height, NSLayoutRelation.Equal, View, NSLayoutAttribute.Width, 0.5625f, 0), // setting it to this to keep your aspect ratio
NSLayoutConstraint.Create(moviePlayer.View, NSLayoutAttribute.Top, NSLayoutRelation.Equal, View, NSLayoutAttribute.Top, 1, 20),
NSLayoutConstraint.Create(moviePlayer.View, NSLayoutAttribute.Left, NSLayoutRelation.Equal, View, NSLayoutAttribute.Left, 1, 0)
});
View.AddConstraints (new [] {
NSLayoutConstraint.Create(label, NSLayoutAttribute.Width, NSLayoutRelation.Equal, View, NSLayoutAttribute.Width, 1, 0),
NSLayoutConstraint.Create(label, NSLayoutAttribute.Height, NSLayoutRelation.Equal, null, NSLayoutAttribute.NoAttribute, 1, 50),
NSLayoutConstraint.Create(label, NSLayoutAttribute.Top, NSLayoutRelation.Equal, moviePlayer.View, NSLayoutAttribute.Bottom, 1, 0),
NSLayoutConstraint.Create(label, NSLayoutAttribute.Left, NSLayoutRelation.Equal, View, NSLayoutAttribute.Left, 1, 0)
});
View.AddConstraints (new [] {
NSLayoutConstraint.Create(textView, NSLayoutAttribute.Width, NSLayoutRelation.Equal, View, NSLayoutAttribute.Width, 1, 0),
NSLayoutConstraint.Create(textView, NSLayoutAttribute.Bottom, NSLayoutRelation.Equal, View, NSLayoutAttribute.Bottom, 1, 0),
NSLayoutConstraint.Create(textView, NSLayoutAttribute.Top, NSLayoutRelation.Equal, label, NSLayoutAttribute.Bottom, 1, 0),
NSLayoutConstraint.Create(textView, NSLayoutAttribute.Left, NSLayoutRelation.Equal, View, NSLayoutAttribute.Left, 1, 0)
});
}
}
}
这样,您的视图就可以适当地适应屏幕大小,例如iphone4、5、6、6+iPad上的布局。如果您的UITextView
太大,它将滚动显示
关于自动布局的一个很好的教程尝试为所有UI组件设置框架,就像您对播放器所做的那样,如果框架未定义,结果将是不可预测的。感谢您的清理!但是,屏幕上没有显示任何内容(只有一个白色的空白屏幕)。我很困惑。这很奇怪,您可以尝试删除类声明中的
部分
部分,然后删除xib文件和designer.cs文件,因为您在以编程方式设置视图时不需要这些文件。如果这不起作用,你能在添加视图的地方编辑你的问题吗?再次感谢你的慷慨帮助。现在一切正常。