I'm having a confusing problem. I'm only ankle deep in Objective-C so I'll try my best to explain. I have a class, which is a controller that simply declares an NSTextField which is in a nib file.
Here's its declaration in the interface file:
#property (nonatomic, retain) IBOutlet NSTextField *textField;
and in the implementation:
#synthesize textField;
Simple right? But if I call [textField stringValue] on it later on by means of clicking on a submit button then it fails with an unknown selector message (typical if it thinks it can't call that message on that object type). This looked like this:
-(IBAction)send:(id)sender {
NSString* txt = [textField stringValue];
[server send:txt];
}
To fix this, I did the following:
#interface MyController : NSObject {
NSTextField *textField;
}
I've not seen any tutorial/example showing this. They do it without declaring the NSTextField in this section of the interface.
My question is, why in my case do I have to declare it in the interface for it to work?
Related
The original question remains below this update:
So further research indicates that my
"...missing setter or instance variable"
log messages are due to an unhinged .xib.
I originally thought that might be the case which is why I went through the process of re-connecting the outlets and properties in the graphic interface builder, but that seems to have been insufficient to repair the connections.
I restored the outlets as properties rather than iVars and reconnected again, still to no avail. So I'm in the process of remaking the .xib's from scratch. Stay tuned for the results.
Original question follows:
Having declared and synthesized properties in parent and sheet classes, and attempted therein to access the properties by their respective class.property names, Xcode rejects the code.
I posted a similar question recently and deleted it after being told there was not enough info to make a response, so I include here below a mini-app which shows how the relevant setup was in the real app of over 2000 lines of Objective-C, which built and ran properly before I attempted to add the Parent / Sheet properties feature.
I've indicated the compiler error messages with a prefix of ////. When I comment out the erroneous lines, the app with its .xib's builds and runs, dysfunctionally of course.
ParentClass.h
// ParentClass stuff belongs in the original main window controller
#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#interface ParentClass : NSObject
{
IBOutlet NSTextField * messageTextField;
IBOutlet NSButton * proceedButton;
}
#property (assign) IBOutlet NSWindow * window;
#property (strong) NSMutableString * parentPropInfo;
- (IBAction) awakeFromNib;
- (IBAction) doCreate:(id)sender;
#end
ParentClass.m
#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import "ParentDelegate.h"
#import "ParentClass.h"
#import "SheetClass.h"
#implementation ParentClass
ParentDelegate * MyDelegate; // only confirms termination requests
NSWindowController * SheetController;
#synthesize parentPropInfo;
- (IBAction)awakeFromNib {
MyDelegate = [NSApplication sharedApplication].delegate;
MyDelegate.ParentController = self; // BTW, this property assignment works!
SheetController = [[SheetClass alloc] initWithWindowNibName: #"SheetClass"];
messageTextField.stringValue = #"Click Proceed button";
}
- (IBAction)doProceed*emphasized text*:(id)sender {
parentPropInfo = #"Hello!".mutableCopy; // to be read by the sheet
[NSApp runModalForWindow:SheetController.window];
// Sheet is active now until it issues stopModal, then:
messageTextField.stringValue = SheetController.sheetPropInfo; // set by the sheet
////above gets ERROR "Property sheetPropInfo not found on object of type 'NSWindowController *'"
messageTextField.stringValue = SheetController.window.sheetPropInfo;
////above gets ERROR "Property sheetPropInfo not found on object of type 'NSWindow *'"
[NSApp endSheet: SheetController.window];
[SheetController.window orderOut:self];
}
#end
SheetClass.h
#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import "ParentClass.h"
#interface SheetClass : NSWindowController
{
IBOutlet NSTextField * propTextField;
IBOutlet NSButton * cancelButton;
}
#property (assign) IBOutlet NSWindow * window;
#property NSMutableString * sheetPropInfo;
- (IBAction)awakeFromNib;
- (IBAction)doCancel:(id)sender;
#end
SheetClass.m
#import "SheetClass.h"
#import "ParentClass.h"
#implementation SheetClass
#synthesize sheetPropInfo;
- (IBAction)awakeFromNib {
propTextField.stringValue = self.window.sheetParent.parentPropInfo; // set by the parent
////above gets ERROR "Property parentPropInfo not found on object of type 'NSWindow *'"
sheetPropInfo = #"Goodbye!".mutableCopy; // to be read by the parent
}
- (IBAction)doCancel:(id)sender {
[NSApp stopModal];
}
#end
I can find nothing in Apple documentation or extensive (three weeks now!) online search to offer any insight as to my abysmal ignorance. I apologize for the overwhelming batch of code needed to illustrate my problem! Where shall I obtain the information I need?
The error messages are perfectly clear. Just read them and think about them. Let's just take the first one. You are saying:
messageTextField.stringValue = SheetController.sheetPropInfo;
...and getting this response from the compiler:
// Property sheetPropInfo not found on object of type 'NSWindowController *'
Well, think about the expression SheetController.sheetPropInfo and why the compiler cannot make sense of it. You have declared SheetController as follows:
NSWindowController * SheetController;
So that is all the compiler knows: SheetController is an NSWindowController. Well, sure enough, just as the compiler says, sheetPropInfo is not a property of NSWindowController. It is a property of SheetClass (which is not the same as NSWindowController; it is a subclass of NSWindowController).
If you know that SheetController is in fact a SheetClass instance, you need to tell the compiler that fact. You must either declare SheetController as a SheetClass or cast it down from an NSWindowController to a SheetClass.
I have a Model Class like this:
Header:
#interface RTSecurityModel : NSObject
{
NSString *code;
}
#property NSString *code;
#end
Implementation:
#implementation RTSecurityModel
#synthesize code;
#end
Then I have my App Delegate:
Header:
#interface RTAppDelegate : NSObject <NSApplicationDelegate>
{
RTSecurityModel *security;
}
#property (assign) IBOutlet NSWindow *window;
#property RTSecurityModel *security;
#end
Implementation:
#implementation RTAppDelegate
#synthesize security;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
security = [[RTSecurityModel alloc] init];
security.code = #"test";
}
Then in my MainMenu.xib I've create a label and in the Bindings Inspector set "Bind To: App Delegate" with "Model Key Path: security.code".
But nothing is showing when I'm starting my application.
I tried soooo many ways to bind this variable, but no one gave success.
Please help me not to hate XCode and Cocoa!
UPD: http://www.experts-exchange.com/Programming/Languages/C/A_3381-Simple-Binding-Cocoa-GUI-Application-without-Outlets.html
Here is the sample how to set Property and Label value by editing the Text Field
But is there a way to edit Label without editing the Text Field? Or without Text Field at all?
UPD2:
You must not create another instance of Object
security = [[RTSecurityModel alloc] init]; // Kill this
Many many thanks to Viktor Lexington
Instead of using security.code as the model path use code. Use the class RTSecurityModel in the value section of the bindings tab instead of the AppDelegate.
Here is a demo project.
Do not bind the Text Field Cell, use the Text Field.
You can check if a value is null if you fill the Null Placeholder with text, will it show that text instead? Then in time of binding the value it null.
To see your RTSecurityModel in the Interface Builder you must let it know your class, it won't look for it.
Add an Object and then set the custom class of it to RTSecurityModel.
Then you can choose this object and set the referencing outlet to the property in the App Delegate.
Assignment will now be directly reflected in the label.
I can think of two ways to solve this programmatically without Interface Builder:
Key Value Coding
// add an observer for the value on the object that has the method below implemented
[self addObserver: self forKeyPath: #"security.code" options: NSKeyValueObservingOptionNew context: NULL];
// method will be called when the observer has 'seen' a value change
-(void) observeValueForKeyPath: (NSString *)keyPath ofObject: (id) object change: (NSDictionary *) change context: (void *) context {
label.text = ...
}
Use a custom setter for code (#synthesize will still create the getter for you)
- (void)setCode:(NSString *)aString {
label.text = aString;
}
I now know there is no protected method in Objective-C and here is my problem.
I have two viewControllers with many functions and properties that are shared. My vision was to have a BaseViewController holding the shared methods and properties, and from it two classes will inherit and override the needed functionality while using the same variables,
I don't wish to convert the shared functions to public by placing them in the .h file
To help clarify my question I'm adding code :)
#interface BaseViewController ()
#property (strong, nonatomic) IBOutletCollection(UIButton) NSArray *uiButtons;
- (void)setBtns:(NSArray *)p_btns; //tried with & without this line
#end
#implementation BaseViewController
- (void)setBtns:(NSArray *)p_btns {
uiButtons = p_btns;
//do something generic with the buttons (set font, image etc.)
}
#end
#interface DerivedViewController ()
#property (strong, nonatomic) IBOutletCollection(UIButton) NSArray *buttonsConnectedToTheActualView;
#end
#implementation DerivedViewController
- (void) setBtns:(NSArray *)p_btns {
[super setBtns:p_btns];
//do something specific with the buttons (decide if they face up or down according to this class logic)
}
#end
The call to [super setBtns:p_btns]; raises an error:
DerivedGameViewController.m:No visible #interface for 'BaseViewController' declares the selector 'setBtns:'
How can I achieve this? Can someone post a snippet or point to my mistake (in code or concept).
Just create a second header with the protected methods declared in a category. Name and document the header appropriately.
UIGestureRecognizer.h and UIGestureRecognizerSubclass.h may server you as an example.
I have the following ViewController class
#import <UIKit/UIKit.h>
#interface SampleViewController : UIViewController {
IBOutlet UITextField *field1;
}
#property (nonatomic, retain) UITextField *field1;
- (IBAction) method1:(id)sender;
#end
When I change the method1:(id)sender to method1:(UITextField)sender, I get the error "Cannot use an object as a parameter to a method".
I searched and found this post which says "it [using an object as a method parameter] is not a good idea in Objective-C because Objective-C does not allow statically allocated object".
Can anyone point out where I can find a more detailed explanation for this?
Thank you.
You're not passing a pointer of UITextField.
method1:(UITextField)sender
should be
method1:(UITextField *)sender
Objective-C doesn't like it when you pass non-pointers for object types.
Why am I getting these errors?
alt text http://img39.imageshack.us/img39/2203/help.tif
It says:
Error: Request for member "jokeTableView" in something not a struction or union
What does that mean? And why is it breaking. I tried reading about initWithStyle but I just could catch up on it
Here is my .h file:
#import <UIKit/UIKit.h>
#interface TableViewController : UITableViewController {
NSMutableArray *jokes;
IBOutlet UITableView *jokeTableView;
}
#property (nonatomic, retain) NSMutableArray *jokes;
#end
Thanks!
Your object (TableViewController) has no property named jokeTableView.
In order to access jokeTableView with the special dot operator, it needs to be a property. Otherwise you have to access it using Key-Value-Coding compliant methods or directly using the -> operator (or just use it as an ivar and no reference to self):
jokeTableView.delegate = self;
or
self->jokeTableView.delegate = self;
or
[self jokeTableView].delegate = self;
or
#property (retain) UITableView *jokeTableView;
// later...
self.jokeTableView.delegate = self;
Also note, however, that you are setting an outlet in the initializer and this won't work. You'll have to set this in the -[TableViewController awakeFromNib] method since self->jokeTableView will be nil when the initializer is actually called (which happens in IB prior to serializing the object into the nib file).
Since you are doing this at init time, the outlets should be NULL, so this initialization shouldn't do anything. This should be done at awakeFromNib time at the earliest.