如何使用显式 NSLayoutManager、NSTextStorage、NSTextContainer 以编程方式设置 NSTextView？

Question

按照苹果文档，我试图通过它的两个构造函数方法设置一个简单的NSTextView。

我将下面的代码放在内容视图的视图控制器的viewDidAppear 方法中。 textView 是NSTextView 的实例，frameRect 是内容视图的框架。

以下 Swift 代码可以工作（给我一个可编辑的 textView 并在屏幕上显示文本）：

    textView = NSTextView(frame: frameRect!)
    self.view.addSubview(textView)
    textView.textStorage?.appendAttributedString(NSAttributedString(string: "Hello"))

以下内容不起作用（文本视图不可编辑且屏幕上未显示文本）：

    var textStorage = NSTextStorage()
    var layoutManager = NSLayoutManager()
    textStorage.addLayoutManager(layoutManager)
    var textContainer = NSTextContainer(containerSize: frameRect!.size)
    layoutManager.addTextContainer(textContainer)
    textView = NSTextView(frame: frameRect!, textContainer: textContainer)

    textView.editable = true
    textView.selectable = true
    self.view.addSubview(textView)

    textView.textStorage?.appendAttributedString(NSAttributedString(string: "Hello more complex"))

我在第二个示例中做错了什么？我正在尝试遵循 Apple 的“Cocoa Text Architecture Guide”中给出的示例，他们讨论了通过显式实例化其帮助对象网络来设置 NSTextView。

Answer 1

您需要保留对您创建的NSTextStorage 变量的引用。我不太确定这一切的机制，但看起来文本视图只保留对其文本存储对象的弱引用。一旦这个对象超出范围，它就不再可用于文本视图。我想这符合 MVC 设计模式，其中视图（在这种情况下为 NSTextView）意味着独立于它们的模型（NSTextStorage 对象）。

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    @IBOutlet weak var window: NSWindow!

    var textView: NSTextView!
    var textStorage: NSTextStorage! // STORE A REFERENCE

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        var view = window.contentView as NSView
        textStorage = NSTextStorage()
        var layoutManager = NSLayoutManager()
        textStorage.addLayoutManager(layoutManager)
        var textContainer = NSTextContainer(containerSize: view.bounds.size)
        layoutManager.addTextContainer(textContainer)
        textView = NSTextView(frame: view.bounds, textContainer: textContainer)

        textView.editable = true
        textView.selectable = true
        view.addSubview(textView)

        textView.textStorage?.appendAttributedString(NSAttributedString(string: "Hello more complex"))
    }
}

Answer 2

在 Xcode 12.4 下测试。在游乐场：

import Cocoa
import AppKit

let textViewFrame = CGRect(x: 0, y: 0, width: 250, height: 90)
let textStorage = NSTextStorage()
var layoutManager = NSLayoutManager()
textStorage.addLayoutManager(layoutManager)
var textContainer = NSTextContainer(containerSize: textViewFrame.size)
layoutManager.addTextContainer(textContainer)
let textView = NSTextView(frame: textViewFrame, textContainer: textContainer)
textView.isEditable = true
textView.isSelectable = true
textView.textColor = NSColor.red
textView.string = "Why is this so complicated..."

Answer 3

#import <Cocoa/Cocoa.h>

@interface TextViewController : NSObject {

    NSLayoutManager *secondLayout;

    IBOutlet NSSplitView *columnView;
    IBOutlet NSTextView *bottomView;

}

- (IBAction) addColumn: (id)sender;

@end
#import "TextViewController.h"

@implementation TextViewController

- (void)awakeFromNib
{
    NSTextStorage *storage = [bottomView textStorage];
    secondLayout = [NSLayoutManager new];
    [storage addLayoutManager: secondLayout];
    [secondLayout release];
    [self addColumn: nil];
    [self addColumn: nil];
}


- (IBAction) addColumn: (id)sender
{
    NSRect frame = [columnView frame];

    NSTextContainer *container = [[NSTextContainer alloc]
                                  initWithContainerSize: frame.size];
    [container setHeightTracksTextView: YES];
    [container setWidthTracksTextView: YES];

    [secondLayout addTextContainer: container];
    [container release];
    NSTextView *newView = [[NSTextView alloc] initWithFrame: frame
                                              textContainer: container];
    [columnView addSubview: newView];
    [newView release];
}

@end