I am creating a program in the iOS SDK in which there is a group of buttons. When a button is clicked, its title is added to an array, and the array is displayed in an assigned label.
When I try to create delete and clear buttons, error messages show up. They show up in the function_builder = function_builder.removeLastObject; and function_builder = function_builder.removeAllObjects; lines of the .m file. The error messages are the same: Assigning to 'NSMutableArray *_strong' from incompatible type 'void'. How do I fix this?
Thank you for any and all help
Here is the .h file:
#import <UIKit/UIKit.h>
#interface SecondViewController : UIViewController
#property (nonatomic,strong) IBOutlet UILabel *equation_field;
#property (nonatomic) NSMutableArray *function_builder;//declare array//
#property(nonatomic, readonly, retain) NSString *currentTitle;//declare button titles//
#end
And here is the .m file:
#import "SecondViewController.h"
#interface SecondViewController ()
#end
#implementation SecondViewController
#synthesize equation_field;
#synthesize currentTitle;
#synthesize function_builder;
NSMutableArray *function_builder;//create the array name//
- (IBAction)functionButtonPress:(UIButton *)sender {//code for all buttons except delete and clear//
[function_builder addObject: sender.currentTitle];//when button is pressed, its title is added to the array//
self.equation_field.text = function_builder.description;//the contents of the array appear in the assigned label//
}
- (IBAction)delete:(UIButton *)sender {//create delete button//
function_builder = function_builder.removeLastObject; //ERROR OCCURRING HERE: Assigning to 'NSMutableArray *_strong' from incompatible type 'void'//
}
- (IBAction)clear:(UIButton *)sender{//create clear button//
function_builder = function_builder.removeAllObjects;//ERROR OCCURRING HERE: Assigning to 'NSMutableArray *_strong' from incompatible type 'void'//
}
- (void)viewDidLoad {
function_builder = [[NSMutableArray alloc] init];//initialize array//
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
} else {
return YES;
}
}
#end
Many errors there..
You've assigned the results of this methods (void*) to function_builder which is of kind NSMutableArray. That makes no sense.
In order to manipulate an object, just send a message to it:
[function_builder removeLastObject]; // this will remove the last object of the array
[function_builder removeAllObjects]; // guess what ;)
For the other thing:
self.equation_field.text = [function_builder componentsJoinedByString:#", "]
This will create a string with all objects in array separated by ", " => A, B, C, D
I think that's just how xCode/objective-c converts arrays to strings(Correct me if I'm wrong), so if you want to format it differently you're going to have to iterate through the string and remove the parentheses and commas, which shouldn't be too hard honestly.
The way I'd do it is read through the string and copy the contents unless they are ( ) or , that way your spacing is still correct and you get the filtering effect that you want.
Related
I have looked all over the place for anyone who has experienced this issue but have yet to find anything relevant, so I thought I'd ask it myself...
I have a custom object (HitterData) which I will use to populate cells in a UITableView, then two ViewControllers (one is hitterTableViewController, the other is a "detail" view controller labeled "AddPlayerViewController").
The problem is that I can add HitterData objects to the NSMutableArray in my Table VC, but only one, and then when I add another one using the detail view controller, the Mutable array is "reinitialized" and I can again only have one object at a time.
HitterObject:
#implementation HitterData.m
#synthesize hitterName = _hitterName;
#synthesize position = _position;
-(id)initWIthNameAndPosition:(NSString *)hitterName position:(NSString *)position {
if ((self = [super init])) {
self.hitterName = _hitterName;
self.position = _position;
}
return self;
}
HitterTableViewController.h
#import "HitterData.h"
#import "HitterDoc.h"
#import "AddPlayerViewController.h"
#interface HitterTableViewController : UITableViewController
#property (nonatomic, strong) NSMutableArray *hitters;
- (IBAction)backButton:(id)sender;
- (IBAction)addPlayerView:(id)sender;
-(void)addHitterObject:(HitterData *)hitter;
HitterTableViewController.m (only relevant to make this more readable)
#implementation HitterTableViewController
#synthesize hitters = _hitters;
- (void)viewDidLoad {
[super viewDidLoad];
self.hitters = [NSMutableArray array];
}
-(void)addHitterObject:(HitterData *)hitter {
if(_hitters != nil) {
[_hitters addObject:hitter];
} else {
_hitters = [NSMutableArray array];
[_hitters addObject:hitter];
NSLog(#"MutableArray is not valid");
}
}
AddPlayerViewController.h
#interface AddPlayerViewController : UIViewController <UITextFieldDelegate, UINavigationControllerDelegate>
#property (weak, nonatomic) IBOutlet UITextField *nameTextField;
#property (weak, nonatomic) IBOutlet UITextField *positionTextField;
#property (nonatomic) HitterTableViewController *hitterTable;
#property (nonatomic) NSString *hitterName;
#property (nonatomic) NSString *position;
//-(void)addNewHitterToHittersArray:(HitterData *)hitter;
- (IBAction)addPlayerToRoster:(id)sender;
AddPlayerViewController.m
#implementation AddPlayerViewController
#synthesize hitterTable;
- (void)viewDidLoad {
[super viewDidLoad];
hitterTable = [[HitterTableViewController alloc] init];
}
- (IBAction)addPlayerToRoster:(id)sender {
self.hitterName = [self.nameTextField text];
self.position = [self.positionTextField text];
HitterData *hitter = [[HitterData alloc] init];
hitter.hitterName = self.hitterName;
hitter.position = self.position;
[hitterTable addHitterObject:hitter];
ArraySingleton *arrayS = [[ArraySingleton alloc] init];
[arrayS initializeArray];
[arrayS addToHittersArray:hitter];
if (arrayS) {
NSLog(#"arrayS exists in AddPlayerVC");
} else {
NSLog(#"arrayS does not exist");
}
[self performSegueWithIdentifier:#"backToTeamTableViewController" sender:self];
}
Am I missing something here?
Guess based just on the code shown:
Every time you wish to add a player it looks like you create a new AddPlayerView/AddPlayerViewController. In turn that controller creates, in its viewDidLoad, a new HitterTableViewController - which of course has its own empty array. The code should instead be referencing the existing HitterTableViewController.
BTW: The common design pattern is MVC - model, view, controller - consider whether you are in your current situation because you've stored part of your model, the array, in your controller, and maybe both controllers should be referencing a common shared model object containing that array.
BTW: All those #synthesise statements are unneeded. In modern Obj-C synthesis is automatic and you rarely need these statements. Also it is generally recommended to not use the property backing variable directly, and certainly not when storing into the property as this breaks KVO. (There also appears to be a related typo in HitterData.m but as you don't report that as not working it is probably just a typo in your question and not code.)
HTH
AddPlayerViewController should know nothing about HitterTableViewController, return the new HitterData object with a delegate method.
- (IBAction)addPlayerToRoster:(id)sender
{
Hitter *hitter = [[Hitter alloc] init];
hitter.name = [self.nameTextField text];
hitter.position = [self.positionTextField text];
[self.delegate didAddHitter:hitter];
}
Then back in HitterTableViewController
- (void)didAddHitter:(Hitter *)hitter
{
[self.hitters addHitter:hitter];
[self dismissViewControllerAnimated:YES completion:nil];
}
I'm trying to teach myself Objective-C and as an exercise, I'm trying to write an app with one button and one label. When I click on the button, I want to trigger a calculation then see the results in the label. The following code compiles and runs with no errors or warnings but as far as I can tell, the [object method] 'call' doesn't do anything. I've spent hours on this and just don't see what's wrong. Can anyone explain the problem? Thanks.
*** testMethodViewController.h ****
#import <UIKit/UIKit.h>
#import "testBrain.h"
#interface testMethodViewController : UIViewController
{
IBOutlet UILabel *display;
testBrain *model;
}
- (IBAction)cellPressed:(UIButton *)sender;
#end
*** testMethodViewController.m ****
#import "testMethodViewController.h"
#implementation testMethodViewController
- (testBrain *)model
{
if (!model) {model = [[testBrain alloc] init];}
return model;
}
- (IBAction)cellPressed:(UIButton *)sender
{
int x = [model check:3]; //This method call doesn't work. But gets no errors.
NSLog(#"Results from model: %i", x); //Says x = 0, but I expect 6
NSString *xAsString = [NSString stringWithFormat: #"testBrain: %i", x];
display.text = xAsString; //Label is updated and displays: testBrain: 0
} //I expect: testBrain: 6
#end
*** testBrain.h ****
#import <Foundation/Foundation.h>
#interface testBrain : NSObject {}
- (int) check:(int) anInteger;
#end
*** testBrain.m ****
#import "testBrain.h"
#implementation testBrain
- (int) check:(int) anInteger //3 passed as the parameter.
{
int r = anInteger + anInteger;
NSLog(#"inside check %i", r); //Debugging line: doesn't print.
return r;
}
#end
When this code runs:
int x = [model check:3];
model is nil. In Objective-C, messages sent to nil silently do nothing, and return 0. So, as you see, x is 0 and -check: is never called.
Apparently you were expecting this method to be called automatically:
- (testBrain *)model
{
if (!model) {model = [[testBrain alloc] init];}
return model;
}
However, that method will be called only if you do it yourself, by saying [self model] or self.model. So, this line would fix it:
int x = [[self model] check:3];
Try it and see.
Going a little further: It would be clearer to remove the model method entirely, and create the instance variable model when the UIViewController is created. That way, we can guarantee that model is valid anytime any code in the testMethodViewController class runs.
You would do that by overriding UIViewController's designated initializer:
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Now you can initialize your instance variables
model = [[testBrain alloc] init];
}
return self;
}
With your model method, you are halfway towards Lazy Instantiation, however to properly achieve this, you must always acess the lazily instantiated object through its accessor method. You aren't doing this in your button action, so your messages are going to nil, which is silently ignored.
This is one of the reasons you often see instance variables in objective-c declared with a leading or trailing underscore. If you then typed model anywhere in the rest of your class, it would be a compiler error, forcing you to use the accessor. Typically this is implemented with properties and the synthesize statement:
In your interface:
#property (nonatomic, strong) TestBrain* model;
In your implementation:
#synthesize model = model_;
Your model method would be:
-(TestBrain*)model
{
if (!model_)
model_ = [[TestBrain alloc] init];
return model_;
}
You would then use self.model instead of model throughout the rest of the class.
If you are just starting out, the Stanford iOS course on iTunes U is an excellent resource, a lot of this sort of material is covered.
int x = [model check:3];
This line should be:
int x = [self.model check:3];
you are almost there. You need to use #property and #synthesize in order to complete this. The #synthesize directive will direct the compiler to create the setters and getters for a particular property. The #synthesize directive tells the compiler that variable is a property. Properties allow you to use the dot syntax. i.e. self.model which will automatically the call the getter or setter method, depending on the context.
In your testMethodViewController.h file change it to look like this:
#interface testMethodViewController : UIViewController
{
IBOutlet UILabel *display;
testBrain *model;
}
#property (nonatomic,retain) testBrain *model;
- (IBAction)cellPressed:(UIButton *)sender;
#end
then in the .m implementation you need to use #synthesize after the #implementation. Like this:
#implementation testMethodViewController
#synthesize model; // tells the compiler to synthesize the setter and getter for you
- (testBrain *)model
{
if (!model) {model = [[testBrain alloc] init];}
return model;
}
then in your cellPressed: method, you need to use self.model in order for the getter to be called:
- (IBAction)cellPressed:(UIButton *)sender
{
int x = [self.model check:3]; //This method call doesn't work. But gets no errors.
NSLog(#"Results from model: %i", x); //Says x = 0, but I expect 6
NSString *xAsString = [NSString stringWithFormat: #"testBrain: %i", x];
display.text = xAsString; //Label is updated and displays: testBrain: 0
}
Hope this helps.
I dont see anywhere in the testMethodViewController.h file
IBOutlet UIButton *button;
Also check if u have properly connected all IBOutlet, IBAction & delegate, datasource.
Ok, I think the question I had here was long-winded and difficult to get through. I'll simplify my question:
I have a class called InController.
InController has a method called nextPage that tells an int variable, inPageNumber, to add one onto itself and to call on another InController method called updateTable.
updateTable clears a table, inTable, of its current data and fills it with data relevant to the page number it retrieves from inPageNumber.
The table, inTable, is contained inside an NSBox with specific printing requirements.
I subclassed NSBox into a class called CustomViewPagination to meet these printing requirements, overriding its paginations methods. Basically, when a new printing page is required, it attempts to print the same area again, but calls on nextPage to fill the table with the data of the sequential page.
With me so far?
One of the pagination methods I overrided in CustomViewPagination, beginPageInRect, is automatically called for each printed page by default. Because of this, I placed a call to my InController method of nextPage, to change the inTable data for the current printing page.
My problem is when I call nextPage (which is a method in InController) from my CustomViewPagination class. It does nothing and when I debug it I find that all the variables required in the method are nil. However, they are the correct values when I call nextPage from inside InController.
File Extracts:
InController.h:
#import <Cocoa/Cocoa.h>
#import "CustomViewPagination.h"
#interface InController : NSObject {
IBOutlet NSWindow *inPreview;
IBOutlet CustomViewPagination *inSheet;
NSArray *iSelectedIn;
NSMutableArray *records;
int inPageNumber;
}
#property (nonatomic, retain) NSArray *iSelectedIn;
#property (nonatomic, retain) NSMutableArray *records;
InController.m:
#import "InController.h"
#implementation InController
#synthesize iSelectedIn, records;
- (IBAction) inNextPage:(id)sender {
inPageNumber = inPageNumber + 1;
NSLog(#"inPageNumber called ok");
[self updateIn];
}
- (IBAction)updateInvoice:(id)sender {
//wipe all current records and refresh empty table
[records removeAllObjects];
[inPreviewTable reloadData];
for (NSArray *s in [[iSelectedIn valueForKey:#"inJobList"] lastObject]) {
NSString *jLT = [s valueForKey:#"inJT"];
NSString *jLH = [s valueForKey:#"inJHo"];
NSString *jLC = [s valueForKey:#"inJC"];
// etc.
// if CustomViewPagination called this, records is nil, so nothing
// is cleared, and there's no *s for iSelectedIn as iSelectedIn
// is found to be nil. If InController called this, it works fine.
CustomViewPagination.h:
#import <Cocoa/Cocoa.h>
#class InController;
#interface CustomViewPagination : NSBox {
InController *inControllerInstance;
}
#end
CustomViewPagination.m:
#import "CustomViewPagination.h"
#import "InController.h"
#implementation CustomViewPagination
- (void) awakeFromNib {
inControllerInstance = [[InController alloc] init];
}
- (void)beginPageInRect:(NSRect)aRect atPlacement:(NSPoint)location {
int pageCounter = [[NSPrintOperation currentOperation] currentPage];
if (pageCounter == 1) {
// Don't respond to 1st page, do nothing.
} else {
[inControllerInstance inNextPage:self];
}
[super beginPageInRect:aRect atPlacement:location];
}
#end
You are using 2 IBOutlets in InController (inPreview & inSheet), but InController is created programmatically in CustomViewPagination's awakeFromNib.
How are the Outlets connected? (Can't be from within IB, as you are creating the InController instance programmatically). This would be an explanation why both are nil.
I'm new to objective-c and I'm finding that I don't know how to correctly assert that a text property on some given label is equal to a raw string value. I'm not sure if I just need to cast the label as NSString or if I need to modify my assert statement directly.
#interface MoreTest : SenTestCase {
MagiczzTestingViewController* controller;
}
- (void) testObj;
#end
#implementation MoreTest
- (void) setUp
{
controller = [[MagiczzTestingViewController alloc] init];
}
- (void) tearDown
{
[controller release];
}
- (void) testObj
{
controller.doMagic;
STAssertEquals(#"hehe", controller.label.text, #"should be hehe, was %d instead", valtxt);
}
#end
The implementation of my doMagic method is below
#interface MagiczzTestingViewController : UIViewController {
IBOutlet UILabel *label;
}
#property (nonatomic, retain) UILabel *label;
- (void) doMagic;
#end
#implementation MagiczzTestingViewController
#synthesize label;
- (void) doMagic
{
label.text = #"hehe";
}
- (void)dealloc {
[label release];
[super dealloc];
}
#end
The build is fine when I modify the assert to compare a raw NSString to another but when I try to capture the text value (assuming it's of type NSString) it fails. Any help would be much appreciated!
STAssertEquals() checks for identity of the two values provided, so it's equivalent to doing this:
STAssertTrue(#"hehe" == controller.label.text, ...);
Instead, you want STAssertEqualObjects(), which will actually run an isEqual: check like the following:
STAssertTrue([#"hehe" isEqual:controller.label.text], ...);
You need to load the nib of the view controller. Otherwise there won't be any objects for the label outlet to be hooked up to.
One way to do this is to add an ivar for the view controller's view to your test case:
#interface MoreTest : SenTestCase {
MagiczzTestingViewController *controller;
UIView *view;
}
#end
#implementation MoreTest
- (void)setUp
{
[super setUp];
controller = [[MagiczzTestingViewController alloc] init];
view = controller.view; // owned by controller
}
- (void)tearDown
{
view = nil; // owned by controller
[controller release];
[super tearDown];
}
- (void)testViewExists
{
STAssertNotNil(view,
#"The view controller should have an associated view.");
}
- (void)testObj
{
[controller doMagic];
STAssertEqualObjects(#"hehe", controller.label.text,
#"The label should contain the appropriate text after magic.");
}
#end
Note that you also need to invoke super's -setUp and -tearDown methods appropriately from within yours.
Finally, do not use dot syntax for method invocation, it is not a generic replacement for bracket syntax in message expressions. Use dot syntax only for getting and setting object state.
I've been stuck on this for days and each time I come back to it I keep making my code more and more confusing to myself, lol. Here's what I'm trying to do. I have table list of charges, I tap on one and brings up a model view with charge details. Now when the model is presented a object is created to fetch a XML list of users and parses it and returns a NSMutableArray via a custom delegate. I then have a button that presents a picker popover, when the popover view is called the user array is used in an initWithArray call to the popover view. I know the data in the array is right, but when [pickerUsers count] is called I get an EXC_BAD_ACCESS. I assume it's a memory/ownership issue but nothing seems to help. Any help would be appreciated.
Relevant code snippets:
Charge Popover (Charge details model view):
#interface ChargePopoverViewController .....
NSMutableArray *pickerUserList;
#property (nonatomic, retain) NSMutableArray *pickerUserList;
#implementation ChargePopoverViewController
#synthesize whoOwesPickerButton, pickerUserList;
- (void)viewDidLoad {
JEHWebAPIPickerUsers *fetcher = [[JEHWebAPIPickerUsers alloc] init];
fetcher.delegate = self;
[fetcher fetchUsers];
}
-(void) JEHWebAPIFetchedUsers:(NSMutableArray *)theData {
[pickerUserList release];
pickerUserList = theData;
}
- (void) pickWhoPaid: (id) sender {
UserPickerViewController* content = [[UserPickerViewController alloc] initWithArray:pickerUserList];
UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:content];
[popover presentPopoverFromRect:whoPaidPickerButton.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
content.delegate = self;
}
User Picker View Controller
#interface UserPickerViewController .....
NSMutableArray *pickerUsers;
#property(nonatomic, retain) NSMutableArray *pickerUsers;
#implementation UserPickerViewController
#synthesize pickerUsers;
-(UserPickerViewController*) initWithArray:(NSMutableArray *)theUsers {
self = [super init];
if ( self ) {
self.pickerUsers = theUsers;
}
return self;
}
- (NSInteger)pickerView:(UIPickerView *)thePickerView numberOfRowsInComponent:(NSInteger)component {
// Dies Here EXC_BAD_ACCESS, but NSLog(#"The content of array is%#",pickerUsers); shows correct array data
return [pickerUsers count];
}
I can provide additional code if it might help. Thanks in advance.
You declare the ivar holding the array as this...
#property (nonatomic, retain) NSMutableArray *pickerUserList;
But then you have a method implemented like this:
-(void) JEHWebAPIFetchedUsers:(NSMutableArray *)theData {
[pickerUserList release];
pickerUserList = theData;
}
You aren't retaining theData and you aren't calling the synthesized setter. If you did Build and Analyze, it should catch this problem and tell you about it. If not, file a bug.