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Mac Forum / Programming / Mac Programming / August 2005Obtaining textfield within a window
Assuming I have a pointer to an NSPanel, say, can I obtain pointers to its NSTextField objects? I realize that one way to do this is make a class in IB, create outlets for each textfield I'm interested in, and control-click-drag to connect the class to the textfields. But can I do that from code at runtime instead? There area bunch of textfields and it seems cluttering to have gobs of member variables pointing at each individual textfield, plus, I don't need the textfield pointers as permament member variables. I just need them briefly from time to time. Can I directly ask for them somehow? The NSPanel and NSWindow classes don't have any obvious looking functions (messages) for obtaining control objects contained within themselves. I'm a little surprised. Thanks. ________________________________________________________________________ Keith Wiley kwiley@cs.unm.edu http://www.unm.edu/~keithw "Yet mark his perfect self-contentment, and hence learn his lesson, that to be self-contented is to be vile and ignorant, and that to aspire is better than to be blindly and impotently happy." -- Edwin A. Abbott, Flatland ________________________________________________________________________ > But can I do that from code at runtime instead? There area bunch of > textfields and it seems cluttering to have gobs of member variables > pointing at each individual textfield, plus, I don't need the textfield > pointers as permament member variables. I just need them briefly from > time to time. You could subclass the panel and give it one or more methods that returns those textfields. > Can I directly ask for them somehow? The NSPanel and NSWindow classes > don't have any obvious looking functions (messages) for obtaining > control objects contained within themselves. I'm a little surprised. No, but I'm sure at least your panel knows its fields and probably has them stored as variables. So by giving it a method other objects can ask the panel for that information.  SignatureI believe in Karma. That means I can do bad things to people all day long and I assume they deserve it. Dogbert > There area bunch of textfields and it seems cluttering to have gobs of > member variables pointing at each individual textfield, plus, I don't need [quoted text clipped - 4 lines] > don't have any obvious looking functions (messages) for obtaining control > objects contained within themselves. I'm a little surprised. use: NSTextField *field = [[panel contentView] viewWithTag:tag]; where panel is some NSWindow object pointer and tag is simply an int you can set in the IB inspector. patrick > use: > > NSTextField *field = [[panel contentView] viewWithTag:tag]; > > where panel is some NSWindow object pointer and tag is simply an int you > can set in the IB inspector. Works like a charm. I'm didn't realize that panel function I needed was contentView. Thanks. ________________________________________________________________________ Keith Wiley kwiley@cs.unm.edu http://www.unm.edu/~keithw "Yet mark his perfect self-contentment, and hence learn his lesson, that to be self-contented is to be vile and ignorant, and that to aspire is better than to be blindly and impotently happy." -- Edwin A. Abbott, Flatland ________________________________________________________________________ > Assuming I have a pointer to an NSPanel, say, can I obtain pointers to > its NSTextField objects? I realize that one way to do this is make a > class in IB, create outlets for each textfield I'm interested in, and > control-click-drag to connect the class to the textfields. This is the usual way to do such things. You have a controller object that has outlets to the views that it cares about. Starting with Panther, you could also just use one of the reusable controllers and bind the value of that text field through a controller to a model object. In this case, you wouldn't need an outlet to the text field, because you wouldn't have code that cares about the text field itself at all. > But can I do that from code at runtime instead? There area bunch of > textfields and it seems cluttering to have gobs of member variables > pointing at each individual textfield, plus, I don't need the textfield > pointers as permament member variables. I just need them briefly from > time to time. You *can* do this -- it's just a matter of walking the view hierarchy -- but this is not the typical way things are done in Cocoa. Either use outlets to refer to the text fields explicitly, or use bindings on the text fields so you never need to manipulate them directly at all. > Can I directly ask for them somehow? The NSPanel and NSWindow classes > don't have any obvious looking functions (messages) for obtaining > control objects contained within themselves. I'm a little surprised. Controls are just a special kind of view. You can get your window's content view, and then walk the view hierarchy. But because Cocoa is designed to use outlets in this situation, you'll have to figure out your own way of identifying which controls you care about. You could use tags for this if you really wanted to. But I would *strongly* encourage you to use either outlets or bindings instead, since that's how the framework is intended to be used. -- Chris > This is the usual way to do such things. You have a controller object that > has outlets to the views that it cares about. and if a panel has numerous textfields, then it would be appropriate for the subclass I create to have a large number of outlets? It seems like a "crowded" approach, but if that's the "right" way, I want to learn it right. I'm just not sure if that is the right way. For example, I'm making a high scores panel for a game. I have twenty text fields, ten names, and ten scores. Do I actually create twenty outlets in IB, and control-click-drag twenty times to connect the outlets? Or is this a situation where accessing the textfields through the contextView (using tags as unique identifers) is an acceptable approach? I already have it working using the contextView and tags, but if making a bunch of outlets is the "cocoa" way to do it, I would rather go back and do it right. > Starting with Panther, you could also just use one of the reusable > controllers and bind the value of that text field through a controller to a > model object. In this case, you wouldn't need an outlet to the text field, > because you wouldn't have code that cares about the text field itself at all. Hmmm, does that give me two way access to the textfields? I need to write to them to write the player names and high scores, but I also need to read from one of them when the panel is done since the user types in his name if he gets a high score. So I need both read and write access to the textfields. I looked up bindings on dev.apple.com and didn't get many hits btw. > you really wanted to. But I would *strongly* encourage you to use either > outlets or bindings instead, since that's how the framework is intended to be > used. Cool. Thanks. ________________________________________________________________________ Keith Wiley kwiley@cs.unm.edu http://www.unm.edu/~keithw "Yet mark his perfect self-contentment, and hence learn his lesson, that to be self-contented is to be vile and ignorant, and that to aspire is better than to be blindly and impotently happy." -- Edwin A. Abbott, Flatland ________________________________________________________________________ > and if a panel has numerous textfields, then it would be appropriate > for the subclass I create to have a large number of outlets? It seems > like a "crowded" approach, but if that's the "right" way, I want to > learn it right. It is the right way, but I want to be clear about something: The controller I'm suggesting shouldn't be a subclass of NSPanel. Generally you would only subclass NSPanel, NSWindow, etc. if you're creating a new-kind-of-panel or new-kind-of-window (e.g. a round window) rather than just putting-stuff-in. > I'm just not sure if that is the right way. For example, I'm making a > high scores panel for a game. I have twenty text fields, ten names, > and ten scores. Do I actually create twenty outlets in IB, and > control-click-drag twenty times to connect the outlets? Or is this a > situation where accessing the textfields through the contextView (using > tags as unique identifers) is an acceptable approach? For something like that, it might be more worthwhile to use an NSForm or NSMatrix. These let you index into a collection of cells (either by index, or by row/column), which may fit what you're trying to do more closely. > Hmmm, does that give me two way access to the textfields? I need to > write to them to write the player names and high scores, but I also > need to read from one of them when the panel is done since the user > types in his name if he gets a high score. So I need both read and > write access to the textfields. When you change the value of a bound property in a model object, anything bound to that property will be updated to reflect the new value. When you manipulate a view that is bound to a property of a model object, the property will be changed accordingly. (And anything else bound to that property will be updated to reflect the new value.) > I looked up bindings on dev.apple.com and didn't get many hits btw. I just searched developer.apple.com for "cocoa bindings" (no quotes) using the search field on the main page. I got back 459 hits, the first five of which are: Cocoa Bindings Programming Topic: What Are Cocoa Bindings? Developing Cocoa Applications Using Bindings: A Tutorial Cocoa Bindings Programming Topic: Troubleshooting Cocoa Bindings Cocoa Bindings Programming Topics: Introduction to Cocoa Bindings Cocoa Performance Guidelines: Cocoa Bindings Tips There should be a lot of information on bindings available from both developer.apple.com and in the ADC Reference Library accessible via Xcode. I'll grant that the first few hits if you search for just "bindings" are WebObjects-related. -- Chris > > But I would *strongly* encourage you to use either outlets or bindings > > instead, since that's how the framework is intended to be used. > > Cool. Thanks. All methods of getting a reference to the text field are equally valid. They are _all_ in the framework, and they are in there to be used. Use the method that suits your needs best. Depending on the situation that may be enumerating an NSMatrix, using Bindings, or indeed -viewWithTag: patrick > All methods of getting a reference to the text field are equally valid. > They are _all_ in the framework, and they are in there to be used. Use > the method that suits your needs best. Depending on the situation that > may be enumerating an NSMatrix, using Bindings, or indeed -viewWithTag: :-) Appreciate the support. Cheers! ________________________________________________________________________ Keith Wiley kwiley@cs.unm.edu http://www.unm.edu/~keithw "Yet mark his perfect self-contentment, and hence learn his lesson, that to be self-contented is to be vile and ignorant, and that to aspire is better than to be blindly and impotently happy." -- Edwin A. Abbott, Flatland ________________________________________________________________________ |
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