If I have viewController1 and viewController2 and user enters a double value into a textField in viewController1 this is passed to a variable in viewController2 and that value can be used.
This variable must then be able to be transferred to the UIView as that is what requires the value.
I'm struggling even at the first hurdle and that is to make a double a #property or what it needs to be, A lot of tutorials and examples show NSStrings being transferred but it is important that I transfer a double.
Here's what I have so far..
ViewControllerInputs.h - viewcontroller1
#interface ViewControllerInputs : UIViewController {
IBOutlet UITextField *thicknessField;
IBOutlet UITextField *capWidthField;
double *thicknessValue;
double *capWidthValue;
}
ViewControllerImage.h - viewcontroller2
#interface ViewControllerImage : UIViewController {
double thicknessValue1;
double capWidthValue1;
}
ViewControllerInputs.m - viewcontroller1
-(IBAction)createWeld {
ViewControllerImage *secondViewController = [[ViewControllerImage alloc]
initWithNibName:#"ViewControllerImage" bundle:nil];
ViewControllerImage.thicknessValue1 = thicknessValue;
//Require modal/push to viewControllerImage
}
UIView inside ViewControllerImage - viewcontroller2
This is where the variables thicknessValue1 and CapWidthValue1 will be used.
You have a few problems:
1) Get rid of the asterisk for each of the double ivars
2) Get rid of the double ivars and use properties instead.
#property (nonatomic, assign) double thicknessValue1;
#property (nonatomic, assign) double capWidthField;
As you have it, you are attempting to assign to a non-existent property.
Use
#property (nonatomic) double someDoubleVariable; for example to define the property, in the interface after defining the instance variable,
#synthesize someDoubleVariable; within the implementation to generate the getter and setter functions.
I suggest you read the documentation on Objective-C 2.0 properties — you're lucky to be programming for a platform whose parent company makes the cleanest documentation. Make good use of it.
Good luck.
Related
i have defined variable in GroupView.h
#interface GroupView()
{
NSMutableArray *chatrooms;
}
#end
#implementation GroupView
Now i want to pass this variable in segue
#interface FriendsViewController ()
#end
#implementation FriendsViewController
else if ([segue.identifier isEqualToString:#"showGroupView"]) {
GroupView *groupView = (GroupView *)segue.destinationViewController;
groupView.chatrooms = [NSMutableArray arrayWithArray:chatrooms];
}
i know that chatrooms has to be property in header file to code this way but it is not
So is there any way to use this variable in segue.
Thanks for help.
chatrooms defined as an ivar like you have done is accessed using -> notation:
groupView->chatrooms = [NSMutableArray arrayWithArray:chatrooms]
This is generally discouraged, though. You should use a property instead:
#interface GroupView
#property (strong) NSMutableArray *chatrooms;
#end
Incidentally, if you're using an NSMutableArray, that indicates that you want to modify the element list of the array directly and not just replace the array wholesale. If you only ever want to replace the array with a whole new array every time, I suggest using NSArray instead.
Another point to make here is that you're attempting to cast the object held at segue.destinationViewController as a GroupView. You have either named a UIViewController subclass in a very misleading way, or you are not accessing the GroupView as a correct member of the UIViewController that is returned to you.
Normally, if you are not building the SDK or something. You don't really have a better reason not to expose it in the header file. However, you can expose the property in the extension and declare a private property in the host class(It's really not able to pass if you just declare a local variable). For example, You have a extension called GroupView+Helper. So, you can pass it into the property exposed in the extension. And then internally translate into the GroupView.
In GroupView.m:
#interface GroupView
#property (strong, nonatomic) NSMutableArray *chatrooms;
#end
In GroupView+Helper.h
#property (strong, nonatomic) NSMutableArray *internalChatrooms;
Also, you need to import the GroupView+Helper in the GroupView.
It will make your chatrooms private and internalChatrooms protected.
I am trying to do the following, and not able to find a straightforward answer.. It is related to this :Passing uitextfield from one view to another. But not exactly.
I have a Firstview.m, from which I push to a Secondview.m. The Secondview.m has a UITextView. I allow the user to edit the UITextView on Secondview.m. Now I want to store this text value in a variable in Firstview.m. One way to to do this is as follows
in Firstview.h
#property (nonatomic) Secondview *secondView;
That is keep a secondView variable in Firstview itself. But this doesn't seem efficient. Ideally I should only have 1 NSString text field in FirstView. What is the right way to do this ? Thanks
You can achieve this by using Delegation in Objective-C.
In your SecondView.h add following right after Header Inclusion
#protocol YourDelegateName <NSObject>
-(void)setText:(NSString *)strData;
#end
Also add delegate property to your header for accessing them in calling class, like below (This goes with other properties declaration in SecondView.h file):
#property (nonatomic, weak) id<YourDelegateName> delegate;
Now, Comes the calling the delegate part. Say, you want to save the text value of UITextView of SeconView in strTextViewData of FirstView class, when the following event occurs:
- (IBAction)save:(id)sender
{
[self.delegate setText:self.txtView.text]; // Assuming txtView is name for UITextView object
}
Now, In FirstView.h add YourDelegateName in delegate list like below:
#interface FisrtView : ViewController <YourDelegateName>
#property (nonatomic, reatin) NSString *strTextViewData;
#end
And then in FisrtView.m file when you create instance of SecondView class, set delegate to self like below:
SecondView *obj = [[SecondView alloc] initWithNibName:#"SeconView" bundle:nil];
obj.delegate = self; // THIS IS THE IMPORTANT PART. DON'T MISS THIS.
Now, Implement the delegate method:
-(void)setText:(NSString *)strData
{
self.strTextViewData = strData;
}
Applying this to your code will do what you want. Also, Delegation is one of the most important feature of Objective-C language, which - by doing this - you will get to learn.
Let me know, if you face any issue with this implementation.
I want to pass whatever string a user inputs into a UITextField' over to the destination view controller, but when I NSLog the value in the destination, it shows up as null. I'm also getting a warning stating:incompatible pointer types assigning to UITextField from NSString`. How can I properly make the assignment and send it over?
Originating view controller
SearchViewController.m:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
controller.itemSearch = self.itemSearch.text;
}
SearchViewController.h:
#property (weak, nonatomic) IBOutlet UITextField *itemSearch;
Destination view controller
UserCategoryChooserViewController.h:
#import <UIKit/UIKit.h>
#import "SearchViewController.h"
#interface UserCategoryChooserViewController : UIViewController
#property (weak, nonatomic) IBOutlet UITextField *itemSearch;
UserCategoryChooserViewController.m:
NSLog(#"The text is:'%#'", self.itemSearch.text); // results in (null)
The above two answer are also correct. But if you want to make the assignment properly then modified textfield variable as NSString variable like that below:
#interface UserCategoryChooserViewController:UIViewController
#property (strong, nonatomic) NSString *itemSearch;
After doing this your warning
incompatible pointer types assigning to UITextField from NSString will get removed
controller.itemSearch is a UITextField *, and you tried to set it to a NSString *, that's what that warning is for. To set text of a UITextField, try this:
[controller.itemSearch setText:self.itemSearch.text];
There might be other issues, but let's start from here.
Let's go through the error you are seeing. It says that you are assigning an NSString * to a UITextField *. Unfortunately, you cannot do that. Here, itemSearch is the text field.
To make your code run properly, you need to set the text property of the itemSearch text field. The correct code would be:
controller.itemSearch.text = self.itemSearch.text;
As a side note, you should really not be meddling so deep into iOS development until you have made a strong foundation, which you have not.
I'm new to objective-c and found some OO features I have learned from other language is different in objective-c. The most confusing question for me until now is how to reimplement a property in subclass, or should I do this?
For example, I have two view controllers GameViewController and CardGameViewController.
#interface GameViewController : UIViewController {
Game *_game;
}
#property (nonatomic) Game *game;
#property (strong, nonatomic) IBOutletCollection(UIButton) NSArray *cardButtons;
#property (weak, nonatomic) IBOutlet UILabel *scoreLabel;
#property (weak, nonatomic) IBOutlet UILabel *messageLabel;
#end
#interface CardGameViewController : GameViewController
#property (nonatomic) CardMatchingGame *game;
#end
CardMatchingGame is derived from Game. #property game in GameViewController is implemented like below:
- (Game *)game
{
if (!_game) {
_game = [[Game alloc] initWithCardCount:[self.cardButtons count]
usingDeck:[self createDeck]];
}
return _game;
}
I tried to reimplement #property game like below but got a warning in the return clause which said Incompatible pointer types returning 'Game *' from a function with result type 'CardMatchingGame *'.
- (CardMatchingGame *)game
{
if (!_game) {
_game = [[CardMatchingGame alloc] initWithCardCount:[self.cardButtons count]
usingDeck:[self createDeck]
matchThreshold:self.threshold.selectedSegmentIndex + 2];
}
return _game;
}
Is this the correct way of reimplementing a property in subclass? If not, what am I supposed to do?
You can't reimplement like that (well, you could do a ton of casting, but that isn't a good option).
One option is to create the property as #property (nonatomic) id game; and then it can hold any type of Game class (or subclass) that you have. And, because it is id type the compiler will assume that any method you try to call is valid. Obviously you could make mistakes which you won't find till later.
Another, better, option is to add a new property in the subclass as #property (nonatomic) CardMatchingGame *cardGame; and, in the subclass, when a new game is created the CardMatchingGame instance is stored in both game and cardGame properties. Now, the superclass has access to game and can use it, and the subclass has access to cardGame, which is typed as the correct class. So, you have compiler checks and usage of the same instance in both classes. But, you haven't reimplemented a property - you have multiple properties, each doing the appropriate task for their location + purpose.
If CardMatchingGame is a subclass of Game you can override - (Game *)game and return your CardMatchingGame object. Just make sure not to change the return type.
I think the problem is ivar in parent class Game *_game; it produce warning you see. Try to use different name or id type for it.
or just cast it before return (CardMatchingGame *)_game;
I'm working on a project in objective C where i have to modificate some variables which are in a view controller from uiviews.
So i've tried somethings like this :
ViewController.h :
#property (nonatomic) bool Contact;
One of the UIViews :
ViewController * View;
View.Contact = YES;
I've also tried to make a setter method like this in the ViewController :
-(void) SetterContact:(bool)boolean;
And so to modificate from a UIView like this :
[View SetterContact:YES];
But it's looking working.
I've read that i have to init the object in which is containt the variable, but in memory management it's not really good to make some initializations from object who are already actives no ?
So if View is already init, i'm not going to call the init method from another UIView no ?
Thanks for your help !
If you want bool variable to be accessible from other viewController.Then simply wirte it as :-
#property BOOL Contact;
and make an object of ViewController in which you have declared contact variable as BOOL and access this variable using like this:-
OtherViewController *otherViewController=[[OtherViewController alloc] init];
otherViewController.Contact=YES;
As it is a instance variable it has to be accessed using class object.
use #property (nonatomic, assign, getter = isContact) BOOL contact; in your .h file.
Respect naming conventions
#property (nonatomic,retain) UIViewController *myController;
don't forget to synthesize
#synthesize myController = _myController;
If you want to implement your own setter do this: respect the naming convention
-(void)setMyController:(UIViewController*)controller;
or if by any bizarre reason you can't respect naming convention you can point the property to the method you want
#property (nonatomic,retain,setter=myBizarreSetterMethod:) UIViewController *myController;
this can help you out as well question in stackoverflow