To start off with I am very new, (about 2.5 weeks) to programming in Objective-C and even newer to writing code for OS X cocoa apps. I am attempting to set the value of a NSTextField label in AppDelegate.m whose IBOutlet property exists in another class. I'm attempting to place this in the - (void)applicationDidFinishLaunching:(NSNotification *)aNotification{} section of AppDelegate.m so that the value of the NSTextField is set before the MainMenu.xib file is loaded and displayed on screen. Here is the following code that I have so far:
AppDelegate.m:
#import "AppDelegate.h"
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification{
// Get Physical memory in MB
MemoryMonitoring *physicalMemoryObj = [[MemoryMonitoring alloc]init];
unsigned long long physicalMemoryValue = [physicalMemoryObj getPhysicalMemoryValue];
// Set the labels on the slider
RamdiskSize *sizeLabels = [[RamdiskSize alloc]init];
NSString *maxValue = [[NSString alloc] initWithFormat:#"%lluGB",(physicalMemoryValue / 1024)];
// This line is not doing what I had expected
[sizeLabels.textLabelSizeMax setStringValue:maxValue];
}
#end
MemoryMonitoring.h:
#import <Foundation/Foundation.h>
#interface MemoryMonitoring : NSObject
-(unsigned long long)getPhysicalMemoryValue;
#end
MemoryMonitoring.m:
#import "MemoryMonitoring.h"
#implementation MemoryMonitoring
-(unsigned long long)getPhysicalMemoryValue{
NSProcessInfo *pinfo = [NSProcessInfo processInfo];
return ([pinfo physicalMemory] /1024/1024);
}
#end
RamdiskSize.h:
#import <Foundation/Foundation.h>
#interface RamdiskSize : NSObject
#property (weak) IBOutlet NSTextField *textLabelSizeMax;
#end
RamdiskSize.m:
#import "RamdiskSize.h"
#import "MemoryMonitoring.h"
#implementation RamdiskSize
#synthesize textLabelSizeMax;
#end
As commented in my AppDelegate.m, the line in question is [sizeLabels.textLabelSizeMax setStringValue:maxValue];. My only other programming experience is from VBScript and as far as I can tell Objective-C uses dot syntaxing to access properties, so this line doesn't seem to be doing what I had expected it to do. If anyone could shed some light on how this is to be done properly, I would greatly appreciate the input.
There needs to be a UIViewController or a subclass of one involved. The textField must be part of a view hierarchy rooted with a view controller's view. Maybe start with a single view application template and add the text field to that view.
Then when that view controller sees viewWillAppear fire, it can ask the MemoryMonitoring class for the value and carry on setting it's own text field.
A good sign that you're on the right track is that you'll need to add virtually nothing to your app delegate code.
Related
I'm testing out some MVVM pattern stuff and seem to have gotten myself confused. Hoping someone here can clarify things for me.
So, what I did was set up a project and added a class that is a subclass of NSObject and called it RootViewModel.
Gave it one method:
- (void) rootTest {
NSLog(#"Booyeah!");
}
In ViewController I imported RootViewModel and made an IBOutlet for it.
#import "ViewController.h"
#import "RootViewModel.h"
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UIButton *btnRunModel;
#property IBOutlet RootViewModel* myModel;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self.myModel rootTest];
}
#end
Then in Storyboard I dragged an Object into the ViewController scene, named it RootModel and connected it to the myModel property in ViewController.
Run the app and it works as expected, Booyeah gets logged.
So now here's where I got messed up. I wanted to set up a unit test. So working in the default unit test file I imported ViewController and made it a property and instantiated it in the set up.
#import <XCTest/XCTest.h>
#import "ViewController.h"
#interface ObjectiveVMMVTests : XCTestCase
#property (nonatomic, strong) ViewController* myViewController;
#end
#implementation ObjectiveVMMVTests
- (void)setUp {
[super setUp];
self.myViewController = [[ViewController alloc] init];
}
Then I tried to create a test where I call the rootTest method.
- (void) testRootModel {
[self.myViewController.myModel rootTest];
}
But I get a compiler error saying myViewController has no property myModel. I assumed it would be there, not sure where I messed this up.
In your unit test, you are saying:
#import "ViewController.h"
That's great. So now the unit test knows that this is a class. But that is not where the myModel property is declared. It is declared in ViewController.m, making this a private property.
Move the property declaration into ViewController.h to make it public so the unit test can see it.
Like #matt said, the IBOutlet is not part of the public interface of ViewController. It's private, hidden in the implementation (.m) file.
You have at least two viable options:
Add #property IBOutlet RootViewModel* myModel; to the ViewController.h file to make it part of the public interface;
Add an interface definition to the ObjectiveVMMVTests unit test file that'll satisfy the compiler:
#interface ViewController ()
#property IBOutlet RootViewModel* myModel;
#end
The implementation of the -(RootViewModel*)myModel getter is there anyway, the compiler just needs to know that ViewController does respond to the message. (You could use performSelector if you weren't interested in the returned object.)
I just like to play with coding for a hobby, so probably a noob question;
I have a simple storyboard for MacOS with 2 views. Both have there own classes (main class and subclass). How can I control a outlet in the subclass from the main class?
for example
I have a button (IBAction) in the mainclass and a textfield (IBOutlet) in the subclass. I want to set the stringvalue for the textfield with a click on the button in main.
I have searched a lot last days but just don't get it. (or just need a push in the right direction)
EDIT after JingJingTao's answer:
I used the control-drag function to open the second window.
I tried the code JingJingTao gives, but the textfield doesn't respond to the action.
My classes look like this now:
ViewController.h
#import <Cocoa/Cocoa.h>
#interface ViewController : NSViewController
- (IBAction)newText:(id)sender;
#end
ViewController.m
#import "ViewController.h"
#import "ViewController2.h"
#interface ViewController ()
#property (nonatomic) ViewController2 *subclass;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (void)setRepresentedObject:(id)representedObject {
[super setRepresentedObject:representedObject];
}
- (void)newText:(id)sender {
self.subclass.textField.stringValue = #"button pressed";
}
#end
ViewController2.h
#import "ViewController.h"
#interface ViewController2 : ViewController
#property (nonatomic) IBOutlet NSTextField *textField;
#end
ViewController2.m
#import "ViewController2.h"
#interface ViewController2 ()
#end
#implementation ViewController2
- (void)viewDidLoad {
[super viewDidLoad];
}
#end
Update:
I've attached two screenshots of what it looks like in the storyboard for the first suggestion,
1) Add a view to your ViewController, set the class at the top right to 'YourView', 'YourView' is a just an NSView, add a textfield to it and hook it up.
2) Add YourView as a property to your ViewController, i.e. #property (nonatomic) IBOutlet NSView *yourView; and hook it up.
Let me know if there are any issues.
You just need to put the textfield in the public interface of your subclass, so you can access it in your main class, although it does sound like you're using inheritance and I don't think you need to but that's another topic :D.
Example:
In MainClassViewController.m
#interface MainClassViewController ()
#propert (nonatomic) Subclass *subclass;
#end
#implementation MainClassViewController
// I guess you already add your subclass to the main viewcontroller because they display on the same screen.
- (void)yourButtonTapMethod {
self.subclass.textfield.text = #"Your value";
}
In Subclass.h
#interface Subclass : NSObject
#property (nonatomic) IBOutlet UITextfield *textfield;
I use Cocoa Touch instead of Cocoa, so maybe it's NSTextfield for you. Please let me know if this does not answer your question, good luck.
what I'm basically trying to make is a very simple program that can switch back and forth between 2 views on a single window.
When the program loads there is a window with a custom view that contains a login button. When clicked, the view changes to a second custom view that contains a label and a logout button. I have this much working.
What I can't figure out is how to get the logout button to bring me back to the first view.
Here is the code for the AppDelegate class where i have the button method to switch the view:
header:
#import <Cocoa/Cocoa.h>
#interface AppDelegate : NSObject <NSApplicationDelegate>
#property (weak) IBOutlet NSWindow *window;
#property (weak) IBOutlet NSView *loginView;
- (IBAction)loginButtonClicked:(id)sender;
#end
implementation:
#import "AppDelegate.h"
#import "myCustomView.h"
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
// Insert code here to initialize your application
}
- (void)applicationWillTerminate:(NSNotification *)aNotification {
// Insert code here to tear down your application
}
- (IBAction)loginButtonClicked:(id)sender {
[_loginView removeFromSuperview];
myCustomView *new = [[myCustomView alloc]initWithNibName:#"myCustomView" bundle:nil];
[[[self window]contentView]addSubview:[new view]];
}
#end
This is the code for my custom class that is a subclass of NSViewController.
header:
#import <Cocoa/Cocoa.h>
#class AppDelegate;
#interface myCustomView : NSViewController
#property (strong) IBOutlet NSView *logoutView;
- (IBAction)logoutButtonClicked:(id)sender;
#end
implementation:
#import "myCustomView.h"
#implementation myCustomView
- (void)viewDidLoad {
[super viewDidLoad];
// Do view setup here.
}
- (IBAction)logoutButtonClicked:(id)sender {
[_logoutView removeFromSuperview];
myCustomView *newController = [[myCustomView alloc]initWithNibName:#"MainMenu" bundle:nil];
[[[self window]contentView]addSubView:[newController view]];
//this does not work. No visible #interface for 'myCustomClass' declares the selector 'window'
}
#end
The button method to go back to the login page is where I'm stuck. Even though I've added the header file for AppDelegate into myCustomClass I cannot use the instance of NSWindow. What am I doing wrong here? Am I at least on the right track? any help here is greatly appreciated.
I also tried using #class instead of #import, but still can't use the instance of NSWindow from AppDelegate.
Here are the pictures of my two xib files:
[][1
UPDATE: The suggestions from Paul Patterson in his comments were very helpful, but haven't solved my problem. For now what I am doing to get my project to work is putting the buttons in the window instead of the views and then hiding them when i don't need them. This works and I can switch back and forth, however I still can't figure out how to use a button on a custom view itself to load a different view onto the same window.
I'm using Xcode to write an app in objective c. I am trying to pass data from a container view controller to the parent view controller using delegation. I have successfully passed the data to the parent view controller, but all of the documentation sets what I have sent to the .h header file in the .m implementation file using viewDidLoad or viewDidAppear. I was wondering, since the view is already present, if there is a way to detect that data has been changed in a view and automatically run a method or code to update the view with the new information. Something along the idea of didReceiveNewData or didEditExistingValues (of course those arent real methods). Thank you for your help!
Edit: What I have done so far:
I want to pass the data from MainFeedTableViewController to MainFeedViewController (The first is in a container inside of the second). I want to set the title of the custom navigation bar in MainFeedViewController to something described in the MainFeedTableViewController.
In the MainFeedTableViewController.m (the view sending data) I have:
#import "MainFeedTableViewController.h"
#import "FeedViewController.h"
#interface MainFeedTableViewController ()
#end
#implementation MainFeedTableViewController
- (IBAction)swipeLeftDetected:(UIGestureRecognizer *)sender {
UIStoryboard *mc = self.storyboard;
FeedViewController *fv = [mc instantiateViewControllerWithIdentifier:#"FeedViewController"];
fv.navigationBarTitleToSet = #"HOPING TO SET TITLE TO THIS";
[self performSegueWithIdentifier:#"MainToLocalFeed" sender:self];
}
and some other unrelated stuff..
In the MainFeedTableViewController.h I have:
#import <UIKit/UIKit.h>
#interface MainFeedTableViewController : UITableViewController
#end
In the MainFeedViewController.m (the one receiving the data) I have:
#import "FeedViewController.h"
#interface FeedViewController () <UINavigationBarDelegate>
#property (weak, nonatomic) IBOutlet UINavigationBar *navigationBar;
#end
#implementation FeedViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (void)setNavigationBarTitle:(NSString *)navigationBarTitle{
self.navigationItem.title = navigationBarTitle;
}
And in the MainFeedViewController.h I have:
#import <UIKit/UIKit.h>
#interface FeedViewController : UIViewController
#property NSString *navigationBarTitleToSet;
#end
I want to run the setNavigationBarTitle method with either data from the .h (navigationBarTitleToSet) or just from the sending view controller, if possible to run a method with delegation. Thanks a ton and I hope this is possible :)
It turns out I needed to add a second navigation bar to account for the container view, allowing me to navigate around the current stack with the parentViewController method and then navigationItem.title. For anyone who happens to find this with a container, make sure you add one immediately after the embed segue. I'm still not sure if you can use methods through delegation, but I can't ponder any situations where it would be necessary anymore, due to viewDidLoad. Thanks to #Tander for the help!
I'm having some trouble understanding what classes can read what variables in other classes. I've read to many different things online and cant seem to find anything solid in here. I've literally wasted the past two days trying to get my program to work but no classes can read any other classes variables. Any help will be GREATLY appreciated.
This is my ViewController.h:
#interface ViewController : UIViewController
{
#public
NSString *nameOfLabel;
}
#property (strong, nonatomic) IBOutlet UILabel *firstLabel;
- (IBAction)Switch:(id)sender;
- (IBAction)changeLabel:(UIButton *)sender;
-(NSString *) nameOfLabel;
#end
nameOfLabel is a public variable and should be able to be accessed by an outside class, right?
ViewController.m:
#import "ViewController.h"
#import "NewView.h"
#interface ViewController ()
#end
#implementation ViewController
- (IBAction)Switch:(id)sender {
NewView * new = [[NewView alloc] initWithNibName:nil bundle:nil];
[self presentViewController: new animated:YES completion:NULL];
}
- (IBAction)changeLabel:(UIButton *)sender {
nameOfLabel = #"Test Name";
_firstLabel.text = nameOfLabel;
}
-(NSString *) nameOfLabel {
return nameOfLabel;
}
#end
changeLabel button changes *firstLabel.text to "Test name".
second class is NewView.h:
#import "ViewController.h"
#interface NewView : UIViewController
#property (strong, nonatomic) IBOutlet UILabel *secondLabel;
- (IBAction)changeSecondLabel:(UIButton *)sender;
#end
and NewView.m:
#import "NewView.h"
#interface NewView ()
#end
#implementation NewView
{
ViewController *view;
}
- (IBAction)changeSecondLabel:(UIButton *)sender {
view = [[ViewController alloc] init];
_secondLabel.text = view.nameOfLabel;
}
#end
changeSecondLabel should change secondLabel.text to nameOfLabel which is 'Test name', however, the label actually disappears which makes me think that nameOfLabel cannot be reached. Ive played around with nameOfLabel, making it a #property and then synthesising it, as well as trying putting it in { NSString *nameOfLabel; } under #implementation but I still get the same result.
This line: view = [[ViewController alloc] init]; creates a new ViewController which doesn't know anything about what you may have done to some other ViewController. In your case, it specifically doesn't know that changeLabel: was called on another ViewController before this new one ever existed.
When the second view controller (NewView) is presented, it has no reference to the first view controller (ViewController) and it's data.
Here are a couple of suggestions.
In modern Objective-C I'd recommend using properties instead of exposing a variable.
Look over the naming in general. "ViewController" is not a good name for example.
If the property is part of an internal state of the class, declare it in a class extension.
Before you present the second view controller, set a reference to the string from the first view controller.
Part of ViewController.m:
#interface ViewController ()
#property (copy,nonatomic) NSString *nameOfLabel;
#end
#implementation ViewController
- (IBAction)Switch:(id)sender {
NewView *new = [[NewView alloc] initWithNibName:nil bundle:nil];
new.secondLabel.text = self.nameOfLabel;
[self presentViewController: new animated:YES completion:NULL];
}
First of all please read about coding standards, it's not a good practice to:
Name variables like "new"
Name methods like "Switch"
Name UIViewController like "view" or "NewView"
Regarding logic:
This is all messed up here. What you actually do is you create viewController with nameOfLabel which is empty and is only changed on button press. I assume you press that button so it's changed. Then on switch action you create another viewController and present it. Then from inside that new viewController you create another new viewController which has empty nameOfLabel, get this empty value and put it inside secondLabel.
There are couple of ways you can do to change secondLabel:
Move nameOfLabel to model and read it from there when you want to change secondLabel,
Because your new viewController is child of viewController that keeps nameOfLabel you can access it by calling [[self presentingViewController] nameOfLabel] but make it property first,
Pass nameOfLabel through designated initializer.
Well, if you want a simple demonstration of access of a public ivar, the syntax is:
view->nameOfLabel;
^^
not dot-syntax:
view.nameOfLabel;
(dot-syntax just goes through accessor methods).
I've only seen a handful of warranted edge cases over the years; there's rarely, rarely ever a good reason to make an ivar public (also, protected is also rarely a good choice).