Creating an instance for other class - ios

I have no idea how I should correctly name the title but I know exactly what my problem is (I will eventually edit the title later).
I am pretty new to Objective-C and I am still learning.
So, I have a class that contains a tableView (I will call it ClassA) and another with a normal UIView (ClassB). What I want to do, is to let a button appear when a row is selected.
I created in my ClassB.h file:
+(id)sharedInstance;
#property (retain, nonatomic) IBOutlet UIButton *btn;
-(void) showBtn :(BOOL) show;
And in my ClassB.m file:
#synthesize btn;
static ClassB *this = nil;
(+id) sharedInstance {
if(!this) {
#synchronized (self) {
this = [[ClassB alloc] init];
}
}
return this;
}
-(void)viewDidLoad {
[self showBtn:NO] //because I only want to let it appear when a row is selected.
[self.view addSubview:btn];
}
-(void) showBtn :(BOOL) show { // I called this method in classA.
if (show == NO) {
btn.hidden = YES;
} else {
btn.hidden = NO;
}
}
So when I launch my app, the button is hidden and stays hidden when I select a row. I debugged, and found that btn is nil when I called the method in ClassA. After some research, I found that the method is called for another instance, so here my question, what can I do, to get it called for the right instance?
EDIT
Here part of my ClassA.m
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
NSInteger row = [indexPath row];
[[ClassB sharedInstance] showBtn:YES];
}

Observation: The ClassB is a UIViewController which is wrong. UIViewControllers have viewDidLoad.
Implementation Suggestion:
The correct implementation for the requirement would be that you create a custom cell with a button. Hide the button in awakeFromNib method. in didSelectRowAtIndex set the cell.button.isHidden = YES.
This should alone take care of the requirement mentioned above.

Related

Change UILabel Text from UiViewController in another UIViewController

Okay it seems like I have made some mistakes and I did not get it with pointer and initializations by now...
Here is the problem :
I have a UIViewController for a registration process called : RegisterViewController
It calls a method in its ViewDidLoad :
[self performSelector:#selector(activateUsernamePopover) withObject:nil afterDelay:0.1];
This method looks like this :
- (void) activateUsernamePopover {
PopoverViewController *popcontroller = [[PopoverViewController alloc] init];
popcontroller.title = nil;
[popcontroller setPopoverText:#"Test"];
FPPopoverController *popover = [[FPPopoverController alloc] initWithViewController:popcontroller];
popover.arrowDirection = FPPopoverArrowDirectionUp;
popover.border = NO;
popover.tint = MgoGreyTint;
[popover setShadowsHidden:true];
[popover presentPopoverFromView:_usernameInput]; }
This will made a Popover visible. This works great.
But I Do have a few more TextFields where I want to show a Popover with a different text.
So I made a method in the PopoverViewController called setPopoverText :
- (void)setPopoverText:(NSString *)text {
[_popoverLabel setText:text];
[_popoverLabel setNeedsDisplay]; }
I call it in my activateUsernamePopover method :
[popcontroller setPopoverText:#"Test"];
And there is the problem.
I can log the text in the PopoverViewControllers method setPopoverText its fine.
But it did not change the text. I logged the _popoverLabel like this :
NSLog(#"%#",_popoverLabel);
and its (null).
I know there is some issue with the pointer or the instance of PopoverViewController I am working with, but objective c is not that clear to me yet.
Anyone got some answers for me ?
How can I change the Text of that UILabel ?
I also could imagine giving the Text to the Controller while instancing it.
Something like that :
PopoverViewController *popcontroller = [[PopoverViewController alloc] initWithPopoverText:#"Test"];
But I don´t know how. I don´t need to change the Text while the popover is visible. It will be released when the user taps in the TextField or elsewhere.
Thanks so far.
Since the UILabel is not created yet when you call init method. the way to do it is to keep text in the NSString property.
In you PopoverViewController, create the init method like this
#interface ViewController : UIViewController
- (id)initWithPopoverText:(NSString *)text;
#end
In the implementation file, keep hold of the text in the property and on viewDidLoad, you could set the text to the label.
#interface PopoverViewController ()
#property (nonatomic) NSString *popoverText;
#end
#implement PopoverViewController
- (id)initWithPopoverText:(NSString *)text {
self = [super init];
if (self) {
_popoverText = text;
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
//set label.text here
self.popoverLabel.text = self.popoverText;
}
#end

Can't see view controller content after pushing to table view controller

I'm new i iOS and Objective-C world, I want to create an example app to learn something but i find some problems in my program.
I Create a TableViewController with Books names, and after touch a book I want see a some more inforamtion about this book.
So I created book class what is a view controller, i created a some Labels inside this class with some text.
NSLogs works fine. After touch the record, apps pushing to new view controller from table view controller worsk good, but I can't see any content over there instead of white bg and back button at the top.
this is book class:
#import "BooksViewController.h"
#interface BooksViewController ()
#end
#implementation BooksViewController
- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
if(self){
self.title = self.bookName;
self.view.backgroundColor = [UIColor whiteColor];
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
UILabel *bookNameLabel = [[UILabel alloc] init];
bookNameLabel.text = self.bookName;
bookNameLabel.frame = CGRectMake(10, 10, 300, 50);
[self.view addSubview:bookNameLabel];
UILabel *authorNameLabel = [[UILabel alloc] init];
authorNameLabel.text = self.authorName;
authorNameLabel.frame = CGRectMake(50, 50, 300, 40);
[self.view addSubview:authorNameLabel];
UILabel *bookDescLabel = [[UILabel alloc] init];
bookDescLabel.text = self.bookDesc;
bookDescLabel.frame = CGRectMake(50, 50, 300, 40);
[self.view addSubview:bookDescLabel];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
this is a methods in table view controller witch I use to create a books inforamtion window:
- (void)viewDidLoad {
[super viewDidLoad];
self.bookNames = #[#"Pan Tadeusz", #"Potop", #"Lalka", #"Uczta dla wron", #"Symfonnia C++"];
self.authorsName = #[#"Adam Mickiewicz", #"Henryk Sienkiewicz", #"Bolesław Prus", #"George R.R Martin", #"Jerzy Greborz"];
self.bookDescs = #[#"Opis Pan Tadeusz", #"Opis Potop", #"Opis Lalka", #"Opis Uczta dla wron", #"Opis Symfonnia C++"];
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Książka na pozycji %ld tapped",indexPath.row);
BooksViewController *bookVC = [[BooksViewController alloc] init];
bookVC.bookName = self.bookNames[indexPath.row];
bookVC.authorName = self.authorsName[indexPath.row];
bookVC.bookDesc = self.bookDescs[indexPath.row];
NSLog(#"Nazwa wybranej książki: %#",bookVC.bookName);
[self.navigationController pushViewController:bookVC animated:YES];
}
You're doing this wrong.
First, create an iVar that will save the Indexpath that the user selected, for that, simply add an NSIndexPath variable at the very top of your .m file.
#implementation yourControllerNameHere (){ //In your code you will have your controller name, just add the NSIndexpath ;)
NSIndexPath *selectedPath;
}
You then need to perform a segue when you select a tableview cell, for that, replace your -didSelectRowAtIndexPath method with this :
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Książka na pozycji %ld tapped",indexPath.row);
selectedPath = indexPath; //We're saving the selected path to our instance variable ! This is very important otherwise we can't find it again.
[self performSegueWithIdentifier:#"fromBooksToDetail"];
}
and add the -prepareForSegue method in your .m file ; it should be there when you first created it ! just find it and add the following
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if([segue.identifier isEqualToString:#"fromBooksToDetail"]){
BooksViewController *bookVC =(BooksViewController*)segue.destinationViewController;
bookVC.bookName = self.bookNames[selectedPath.row];
bookVC.authorName = self.authorsName[selectedPath.row];
bookVC.bookDesc = self.bookDescs[selectedPath.row];
NSLog(#"Nazwa wybranej książki: %#",bookVC.bookName);
}
}
Now this will NOT work unless you add a segue link between your two viewcontrollers in storyboard, so simply open your storyboard and, using a right clic or a ctrl+left clic, drag your mouse from your TableViewController to your BooksController. Don't forget to give it the right identifier in the Attributes Inspector on the right panel !
Note that I wouldn't have named them like that ; BooksViewController has more sense if it's the TableViewController name, and "BookDetailViewController" for the detail page. But that's just a detail.
Once you have the segue link, the performSegue call and the prepareForSegue method, you'll be all set ;)
You need to learn how to debug. Try putting NSLog(#"bookname: %#", self.bookName) in your viewDidLoad and see if you print anything. (Most probably not)
I'm not 100% sure how the view life cycle works when you use alloc init for a view controller. But my bet is that the properties are not set there. Try moving bookNameLabel.text = self.bookName; to viewWillAppear instead of viewDidLoad
You should use storyboards instead. It's super easy.
Also, your initWithNibName will never get called. You are using the init-method.

Setting UILabel text is not working

Here is my .h file
#import <UIKit/UIKit.h>
#interface PersonViewController : UIViewController
#property(strong,nonatomic) NSString *personTitle;
And here is my .m file
#interface PersonViewController ()
#property (weak, nonatomic) IBOutlet UILabel *titleView;
#end
#implementation PersonViewController
//stuff …
-(void)setPersonTitle:(NSString *)personTitle
{
[self.titleView setText:personTitle];// also self.titleView.text=personTitle
[self.titleView setNeedsDisplay];
NSLog(#"The title shoud match as %# :: %#",personTitle,self.titleView.text);
}
-(NSString *)personTitle
{
return self.titleView.text;
}
//… more stuff
#end
The logging shows that the value is (null) for self.titleView.text whereas personTitle prints the appropriate value.
I remember doing this same thing a number of times and it worked. Any ideas why it’s failing this time?
update I use storyboard to set my scenes. And I am using xcode-5 and iOS-7
update: how I call
The user clicks a button, leading to a push segue
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSLog(#"enter prepare for segue.");
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
if ([segue.identifier isEqualToString:the_identifier_for_person]) {
NSLog(#"segue to person is progressing“);
if ([segue.destinationViewController isKindOfClass:[PersonViewController class]]) {
NSLog(#"segue to person destination is a match");
PersonViewController *aPerson = (PersonViewController *)segue.destinationViewController;
aPerson.personTitle=((MyItem*)self.allItems[indexPath.row]).title;
NSLog(#"segue to person is done");
}
}
}
This sounds like you forgot to wire up your UILabel in the storyboard. Can you confirm that self.titleView is not null?
View controllers create their views on demand, but can spot that only via a call to view. When the view is loaded, your outlets will be populated.
Either call view to force loading or keep the string in abeyance until you get viewDidLoad.
(aside: prior to iOS 6, views would also be released in low-memory situations so the idiomatic thing is to store the string and populate on viewDidLoad)
Having accepted another answer, I wanted to show the pattern that I actually used to solve the problem, in case someone else comes looking. This pattern is best practice (yes, I forgot it for a long moment there).
#pragma mark - update UI
-(void)setPersonTitle:(NSString *)personTitle
{
_personTitle=personTitle;
if (self.view.window) [self updateUI];//only if I am on screen; or defer to viewWillAppear
}
-(void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self updateUI];
}
-(void)updateUI
{
self.titleView.text=self.personTitle;
}
It is always important to update the ui when the data has changed, which is why I must make the call inside setPersonTitle. But because the IBOutlets are not yet set when I set personTitle in prepareForSegue, then I must also make the call inside viewWillAppear.
Do you actually call the -(void)setPersonTitle:(NSString *)personTitle method?
It seems that you aren't calling it correctly which would result in the title being null.
After reviewing the prepareForSeque it is clear that you are not calling the method. You are actually just changing the #property named personTitle.
In the viewDidLoad you should have it so that self.titleView.text = self.personTitle;

Passing NSString from one class to another. (ECSlidingViewController?)

Firstly, I've already tried to search for solutions online but none works for me and I'm thinking since I'm using ECSlidingViewController to navigate around the app, I can't utilise the prepareForSegue method thus, my problem may need a different approach.
I have a class called viewInits which holds properties in the .h file that I want allow other classes to set and get it's values. In this case, the property is an NSString *navBarTitle.
In ClassA, I have a tableView:didSelectRowAtIndexPath: method, where I
Create an ViewInits class object - *viewInits.
I then set the setNavBarTitle: to the value of [self.MenuRowsArray objectAtIndex:indexPath.row].
In the next line, I did an NSLog to check and yes, viewInits.navBarTitle now holds the value I desire.
In ClassB's viewDidloadMethod, similarly, I created a ViewInits object - *viewInits and did an NSLog check for viewInits.navBarTitle. But it returns (null). What seems to be the problem here?
Here is the code for how I'm trying to pass the NSString. What am I doing wrong?
viewInit .h
#interface ViewInits : NSObject
#property (strong, nonatomic) NSString *navBarTitle;
#end
ClassA.m tableView:didSelectRowAtIndexPath: method:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *identifier = [self.MenuRowsArray objectAtIndex:indexPath.row];
UIViewController *newTopViewController = [self.storyboard instantiateViewControllerWithIdentifier:identifier];
// *---------- Assign identifier to NSString viewInits ----------*
ViewInits *viewInits = [[ViewInits alloc] init];
[viewInits setNavBarTitle:identifier];
NSLog(#"%#", viewInits.navBarTitle);
// *---------- Assign identifier to NSString viewInits ----------*
[self.slidingViewController anchorTopViewOffScreenTo:ECRight animations:nil onComplete:^
{
CGRect frame = self.slidingViewController.topViewController.view.frame;
self.slidingViewController.topViewController = newTopViewController;
self.slidingViewController.topViewController.view.frame = frame;
[self.slidingViewController resetTopView];
}];
}
ClassB.m
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
// *========== ECSlidingViewController ==========*
self.view.layer.shadowOpacity = 0.75f;
self.view.layer.shadowRadius = 10.0f;
self.view.layer.shadowColor = [UIColor blackColor].CGColor;
if (![self.slidingViewController.underLeftViewController isKindOfClass:[MenuViewController class]])
{
self.slidingViewController.underLeftViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"Menu"];
}
[self.view addGestureRecognizer:self.slidingViewController.panGesture];
// *========== ECSlidingViewController ==========*
ViewInits *viewInits = [[ViewInits alloc] init]; // Create ViewInit class object
self.navBar.topItem.title = viewInits.navBarTitle;
NSLog(#"%#", viewInits.navBarTitle); // <<--- This always ends up null. What's wrong?
}
Your help are much appreciated. Thank you.
If you want to use ViewInit as a common store of settings it should be a singleton so that all other instances in the app can get it. Currently you're creating a new instance each time you want to use it, so the new instance doesn't have any of your previous settings.
Aside, I know what the sliding view controller is, I ask about it because you may be using it incorrectly. If you have a view controller which is the current top view controller and it changes the top view controller (class A might be doing this, not sure) then the reference self.slidingViewController will stop working part way through your code.

iOS - passing Sender (button) name to addSubview

I have a main view with 3 buttons. Clicking on any of the buttons adds a SubView.
The buttons have different titles and are all linked to IBAction "switchView"
The "switchView" code is below.
- (IBAction)switchView:(id)sender{
secondView *myViewController = [[secondView alloc] initWithNibName:#"secondView" bundle:nil];
[self.view addSubview:myViewController.view];
}
The "secondView" loads up correctly and everything works well.
The problem is I want to be able to know which button was the Sender.
I don't want to create 3 subviews, one for each button. The code and XIB would be absolutely the same>
The only difference would be a variable that I would like to set up in the second view (viewDidLoad method) depending on who is the Sender (which button was clicked)
Is this possible? Or I would need to create 3 subViews - one for each button?
Your help is greatly appreciated!
You can identify different buttons with the tag property.
e.g. with your method:
-(IBAction)switchView:(id)sender {
UIButton *button = (UIButton*)sender;
if (button.tag == 1) {
//TODO: Code here...
} else if (button.tag == 2) {
//TODO: Code here...
} else {
//TODO: Code here...
}
}
The tag property can be set via the InterfaceBuilder.
Hope this helps.
I think you can solve in 2 ways:
Create a property like:
#property (nonatomic, strong) IBOutlet UIButton *button1, *button2, *button3;
in your viewcontroller and link the buttons to them as referencing outlet on the XIB.
Give a different tag to each button on your xib and ask for the tag of the sender with UIButton *b=(UIButton*)sender; b.tag; like Markus posted in detail.
Solving my problem it all came down to transferring data between the mainView and subView.
In my mainView.h I declared an NSString and its #property
...
NSString *btnPressed;
}
#property(nonatomic, retain) NSString *btnPressed;
...
then in my mainView.m inside the switchView method I did this:
- (IBAction)switchView:(id)sender{
secondView *myViewController = [[secondView alloc] initWithNibName:#"secondView" bundle:nil];
btnPressed = [NSString stringWithFormat:#"%i", [sender tag]];
[myViewController setBtnPressed:self.btnPressed];
[self.view addSubview:myViewController.view];
}
This line in the code above actually takes care of transferring the data to the newly created subView:
[myViewController setBtnPressed:self.btnPressed];
Then in my secondView.h I declare exactly the same NSString *btnPressed and its #property (though this a completely different object than the one declared in main)
Then in my secondView.m I get the value of the button pressed I'm interested in.
- (void)viewDidLoad {
[super viewDidLoad];
int theValueOfTheButtonPressed = [self.btnPressed intValue];
}
This works well.
Don't forget to #synthesize btnPressed; as well as [btnPressed release]; in both mainView.m and secondView.m

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