English 中文(简体)
Interface Builder won t connect button, but the tutorial says it should work
原标题:

I ve been trying to learn Core Data, and browsing through questions on Stack Overflow lead me to a recommendation that I try the tutorial on Core Data over at Cocoa Dev Central (Link).

Everything is making sense so far in the tutorial, but when I got to step 16, it wouldn t let me connect the + button to the Posts array controller. I ve gone back and double, triple-checked each step along the way and can t see where anything is off, but it still won t let me connect. I m using the latest versions of Xcode and Interface Builder (just re-downloaded them last week); could this be a version compatibility issue?

Addendum

Seems that the problem was in that I had to change the name by changing the class in the inspector, and that removed the default actions for the array controller. Changing the class back to NSArrayController restores functionality, but now it appears as "Array Controller" wherever it appears, which seems like it d become problematic with 3 controllers in play once I fix the Authors and Topics controllers.

最佳回答

Got it. Under the inspector, use "Name" to change the name of the object, not "Class". Newbie error.

问题回答

Based on your comments, you changed the class of the Posts controller from an NSArrayController to a custom class called Posts. Interface builder couldn t find an implementation for this custom class, hence, did not show any actions or outlets available to bind against.

Changing the class back to NSArrayController fixed the problem.

(Interface builder lets you do this as you may want to define your own custom controller. You can add the actions and outlets to the object in IB, then generate the class and add the implementation in XCode. This is quite useful - but can confuse new users of the tool.)





相关问题
Asynchronous request to the server from background thread

I ve got the problem when I tried to do asynchronous requests to server from background thread. I ve never got results of those requests. Simple example which shows the problem: @protocol ...

objective-c: Calling a void function from another controller

i have a void, like -(void) doSomething in a specific controller. i can call it in this controller via [self doSomething], but i don t know how to call this void from another .m file. I want to call ...

ABPersonViewController Usage for displaying contact

Created a View based Project and added a contact to the AddressBook using ABAddressBookRef,ABRecordRef now i wanted to display the added contact ABPersonViewController is the method but how to use in ...

NSArray s, Primitive types and Boxing Oh My!

I m pretty new to the Objective-C world and I have a long history with .net/C# so naturally I m inclined to use my C# wits. Now here s the question: I feel really inclined to create some type of ...

NSUndoManager and runModalForWindow:

I have a simple Core Data app which displays a list of entities in the main window. To create or add new entities, I use a second modal window with a separate managed object context so changes can be ...

NSMutableArray values becoming "invalid"

I m trying to show a database information in a tableview and then the detailed information in a view my problem is as follow: I created a NSMutableArray: NSMutableArray *myArray = [[NSMutableArray ...

iPhone numberpad with decimal point

I am writing an iPhone application which requires the user to enter several values that may contain a decimal point (currency values, percentages etc.). The number of decimal places in the values ...

热门标签