I'll write an application which show the current time with a button to update. It looks like this:
This application is very easy. Just to show how to use "outlet" and "action" in Gorm, and the relation between "controller" and "view".
Open Gorm, choose "Document->New Application", and build a window with a title and a button.
You can set the title of the button in the inspector. So does the title of window.
That's all I need to do on the interface.
Now, I need an "controller" to receive the action from the "view", and display the time on the "view". I need to create a object for this "controller".
First, I need to design the class of this "controller". Click the "classes" in the main window of Gorm.
It will show all the classes you can use. I want the class of this "controller" to inherit from NSObject. Therefore, choose "NSObject", then select the menu "Classes->Create Subclass...". It will create a new class under the NSObject.
Double-click on it to change the name. I call it "Controller" here. That's the name of this class.
Then I need a "outlet" in this class to connect to the label in the window, and an "action" which is triggered when the button is press.
Choose the "Controller" class and click "Outlets" tab in the inspector. Press "Add" button, and change the name to "label" by double-clicking the "newOutlet". You will notice that "Controller" class now has one outlet. Click on the small round button will list the outlets it has.
Now, click "Actions" tab and add a new action called "showCurrentTime:". You should notice that the action is ended with colon (:), which will be explained later.
Once I finish designing this class, I can create an instance from it.
Choose the class "Controller", then select the menu "Classes->Instantiate". Look at the objects of Gorm main window. You should find a new instance, called "Controller". That's the instance I want to connect to the interface.
Now, I can connect the "controller" to the "view" for the outlet. Hold on "Ctrl", select the "Controller" instance, drag to the label in the window. Look at the inspector, which will show all the outlet the "Controller" instance has. Select the only one "label", click the "connect" button. That's it.
Again, I can connect the "view" to the "controller" for the action. Hold on "Ctrl", select the button in the window, drag to the "Controller" instance. Look at the inspector, which will show all the outlet the button has. Select the "target" in the outlet column, then select the only one action the target has, "showCurrentTime". Click the "connect" button. That's it.
Finally, I need to create the files for this "Controller" class in order to add the the source code. Otherwise, this class has not function at all. Select the class "Controller" ( not the instance !) in the Gorm main window. Choose menu "Classes->Create Class Files". A "Save" panel will show up and ask the filename. The default is "Controller.m", which is good enough. Click "O.K.". Save this Gorm file as "TimeMachine.gorm", then leave Gorm.
Now, I have a directory, "TimeMachine.gorm", and two file, "Controller.h" and "Controller.m".
Controller.h:
/* All Rights reserved */
#import <AppKit/AppKit.h>
@interface Controller : NSObject
{
id label;
}
- (void) showCurrentTime: (id)sender;
@end
Controller.m:
/* All Rights reserved */
#import <AppKit/AppKit.h>
#import "Controller.h"
@implementation Controller
- (void) showCurrentTime: (id)sender
{
/* insert your code here */
}
That's the source code of the class "Controller" I just created in Gorm. The method -showCurrentTime: has the message "sender". That's the reason the action name in Gorm must has the colon (:) in the end. In the "Controller.h", you can find the outlet "label" and the action "showCurrentTime:". Therefore, whatever you do on the outlet "label" will reflect to the "label" in the interface, and when the button "Get Current Time" is pressed, the action -showCurrentTime: will be called. That's how the outlet and action work.
Now, I can put some source code in this class.
Controller.m:
/* All Rights reserved */
#import <AppKit/AppKit.h>
#import "Controller.h"
@implementation Controller
- (void) showCurrentTime: (id)sender
{
/* insert your code here */
NSCalendarDate *date = [NSCalendarDate date];
[date setCalendarFormat: @"%H : %M : %S"];
[label setStringValue: [date description]];
}
First, [NSCalendarDate date] will create an instance with the current date and time. After setting the format, put the description of current time into the outlet "label". When users click the "Get Current Time" button, it will show the current time.
That's it. Add the main.m and GNUmakefile, then it is ready to go.
main.m:
#import <AppKit/AppKit.h>
int main(int argc, const char *argv[])
{
return NSApplicationMain (argc, argv);
}
GNUmakefile:
include $(GNUSTEP_MAKEFILES)/common.make APP_NAME = TimeMachine TimeMachine_HEADERS = Controller.h TimeMachine_OBJC_FILES = main.m Controller.m TimeMachine_RESOURCE_FILES = TimeMachineInfo.plist TimeMachine.gorm TimeMachine_MAIN_MODEL_FILE = TimeMachine.gorm include $(GNUSTEP_MAKEFILES)/application.make
In this example, the owner of the interface is NSApp, which is the NSOwner in Gorm, but the controller is the "Controller" instance. Sometimes, the owner and the controller could be the same. In simple application, the owner/controller of the window can also be the delegate of NSApp. That's all depending on the design of your application.