Creating an NSTextView Object Programmatically

At times, you may need to assemble the text system programmatically. You can do this in either of two ways: by creating an NSTextView object and letting it create its network of supporting objects or by building the network of objects yourself. In most cases, you’ll find it sufficient to create an NSTextView object and let it create the underlying network of text-handling objects, as discussed in this article. If your application has complex text-layout requirements, you’ll have to create the network yourself; see “Creating Text System Objects” in Cocoa Text Architecture Guide for information.

You create an NSTextView object programmatically in the usual way: by sending the alloc and init... messages. You can also create an NSTextView object using either of these methods:

• initWithFrame:textContainer: (the designated initializer)

• initWithFrame:

The method that takes one argument, initWithFrame:, is the simplest way to obtain an NSTextView object—it creates all the other components of the text system for you. If you use the method that takes two arguments, initWithFrame:textContainer:, you must create the other components yourself.

Listing 1 shows how you can create an NSTextView object, given an NSWindow object represented here by aWindow.

Listing 1  Creating an NSTextView object programmatically

/* determine the size for the NSTextView */

NSRect cFrame =[[aWindow contentView] frame];

/* create the NSTextView and add it to the window */

NSTextView *theTextView = [[NSTextView alloc] initWithFrame:cFrame];

[aWindow setContentView:theTextView];

[aWindow makeKeyAndOrderFront:nil];

[aWindow makeFirstResponder:theTextView];

This code determines the size for the text view’s frame rectangle by asking aWindow for the size of its content view. The NSTextView is then created and made the content view of aWindow using setContentView:. Finally, the makeKeyAndOrderFront: and makeFirstResponder: messages display the window and cause the text view to prepare to accept keyboard input.

The initWithFrame: method not only initializes the receiving NSTextView object, it causes the object to create and interconnect the other components of the text system. This is a convenience that frees you from having to create and interconnect them yourself.