I have an iPad app in progess but I'm having difficulty catching the selection of a row in my table view. I know this is because I haven't defined my delegate properly yet but, after 2 hours on the net, it still isn't making much sense.
What I'm trying to do is pass the selected table row item to a new view that displays info based on the selection - pretty standard.
I set up the tableViewController sub class using the option to create it as a UITableViewController subclass which, unless I am wrong, incorporates the delegates (UITableViewDelegate and UITableViewDataSource) automatically.
In the didSelectRowsAtIndex method I'm trying to create a DetailViewController. I've tried with a nib file and creating one purely in code but the class is never created. I'm missing a step I'm sure of it but I can't find what it is. At some point shouldn't I be defining what function I want to access with the selected row? But where? How?
In what I considered was my best attempt, I created the DetailViewController, set a string variable in the detailViewController to the selected row, and then tried to add the detailViewController view to display. I figured I could then use the viewDidload to call the next function but the view never got displayed on screen.
Some basic guidence would be nice. Or a decent tutorial would be nice. No calls to read the relevant docs please, I've been over it and right now I need a example to pull things together.
Thanks,
Steve
I think you are missing this line in your didSelectRowAtIndexPath: method
[self presentModalViewController:controller animated:YES];
where controller is an object of class DetailViewController
Yeah, maybe paste the code snippet will be easier to figure out what's going on here. And are those delegate(didSelectRowAtIndexPath:) methods being called correctly?
Try this,
this goes in didSelectRowAtIndexPath
MoreInfoTable *moreInfoView = [[MoreInfoTable alloc] initWithStyle:UITableViewStyleGrouped];
//in the MoreInfoTable, make properties like titles etc.
[self.navigationController pushViewController:moreInfoView animated:YES];
[moreInfoView release];
}
here's an example of an MoreInfoTable.h
#interface MoreInfoTable : UITableViewController {
NSMutableArray *moreInfo;
NSURL *getDirections;
NSURL *getWebsite;
NSMutableString *getPhoneNumber;
NSString *address;
NSString *footer;
float lat, lon;
}
-(void)goToWebsite;
-(void)goToMaps;
-(IBAction)addToFavorites:(id)sender;
-(void) callNumber;
#property (nonatomic,retain) NSURL *getDirections;
#property (nonatomic,retain) NSURL *getWebsite;
#property (nonatomic,retain) NSMutableString *getPhoneNumber;
#property (nonatomic,retain) NSString *footer;
#property (nonatomic,retain) NSString *address;
#property (readwrite) float lat;
#property (readwrite) float lon;
#end
now back in the other file in which you declare the table, you can say
MoreInfoTable *moreInfoView = [[MoreInfoTable alloc] initWithStyle:UITableViewStyleGrouped];
//in the MoreInfoTable, make properties like titles etc.
moreInfoView.title = #"TITLE!";
//etc.
[self.navigationController pushViewController:moreInfoView animated:YES];
[moreInfoView release]; //
Related
Im stuck on this problem and it's driving me crazy. What I am attempting to do is have a button click create an instance of a custom class, set it's variables, add it to an NSMutableArray, and display it in a table view. So far it seems that I have everything working except having the info display in the table view.
My custom class TradePaperback just has three NSString properties: title, volume, and publisher.
Here is the code for my header and implementation files:
Header:
#import <Cocoa/Cocoa.h>
#interface AppDelegate : NSObject <NSApplicationDelegate>
#property (nonatomic, strong) NSMutableArray *tradeArray;
#property (weak) IBOutlet NSTableView *tableView;
- (IBAction)addTrade:(id)sender;
#end
implementation file:
#import "AppDelegate.h"
#import "tradePaperback.h"
#interface AppDelegate ()
#property (weak) IBOutlet NSWindow *window;
#end
#implementation AppDelegate
-(NSMutableArray *)tradeArray{
if (!_tradeArray){
_tradeArray = [[NSMutableArray alloc]init];
TradePaperback *avengers = [[TradePaperback alloc]init];
avengers.title = #"Avengers";
avengers.volume= #"volume 01";
avengers.publisher = #"Marvel Comics";
[_tradeArray addObject:avengers];}
return _tradeArray;}
- (IBAction)addTrade:(id)sender {
TradePaperback *newTrade = [[TradePaperback alloc]init];
newTrade.title = #"New Trade";
newTrade.volume = #"Volume Number";
newTrade.publisher = #"publisher";
[_tradeArray addObject:newTrade];
NSLog(#"added");
NSLog(#"number of items in array is %ld", _tradeArray.count);
[_tableView reloadData];}
#end
My table view is hooked up using bindings. It seems that everything is hooked up correctly since the avengers instance of TadePaperback that i put in shows up when I run the program. As I click the add button I can see from the log in the console that the array is having items added to it, but they just won't display.
Why would the tableView show the first item in the array, but none of the rest?
Here is a picture of the program after running and clicking the add button a couple of times.
program running
I would greatly appreciate any help or advice you guys could give. Thanks in advance.
-Jack
If you're using bindings to populate a table view, you're almost certainly using an NSArrayController to manage the table's content. If you want to add an object to the array controlled by this controller (your tradeArray object), you should do so indirectly: add to the array controller, which will in turn update your array. NSArrayController provides a number of add... or insert.. methods; decide which one suits you best, and use it to replace your call to [_tradeArray addObject:...].
The reason this approach works, and yours doesn't is because this engages the key-value coding/observing machinery that underpins bindings. Your approach essentially adds the object behind the array controller's back - it's not KVO/KVC-compliant, so the array controller remains unaware of the change. Cocoa does provide you with a way of editing the original array in a KVO/KVC-friendly manner if you so wish, it's just a little more work: try the code below, then read Apple's NSKeyValueCoding Protocol Reference and their Key-Value Coding Programming Guide for an explanation:
// Instead of [_tradeArray addObject:newTrade];
[[self mutableArrayValueForKey:#"_tradeArray"] addObject:newTrade];
.h file
#import <UIKit/UIKit.h>
#interface calculatorViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *display;
#end
.m file
#import "calculatorViewController.h"
#interface calculatorViewController ()
#end
#implementation calculatorViewController
#synthesize display=_display;
- (IBAction)digitPressed:(UIButton*)sender
{
NSString *digit=[sender currentTitle];
NSLog(#"digit pressed %#", digit);
UILabel*myDisplay=self.display;
//[self display] why not just type
NSString *currentText= myDisplay.text;//[myDisplay text]; why are we not writing current title again?
nsstring*newText=[currentText stringByAppendingString:digit];
[myDisplay setText:newText];
Hi guys!
I have been trying to learn Objective-C so these questions might be stupid for you but tough for me, so please do not down vote my question as I am only trying to learn like you. :)
I have a couple of questions in .m file.
(IBAction)digitPressed:(UIButton*)sender Does (UIButton *) mean that it is a type and that sender is a pointer simultaneously? Cant we remove the bracket?
NSLog(#"digit pressed %#", digit);Why does this not work with *digit. Doesn't digit only store the address and not the actual value?
UILabel*myDisplay=self.display; I know self.display is a getter but what exactly is selfWhen do we use it?
NSString *currentText= myDisplay.text Why are we writing .text and not currentTitle like in NSString *digit=[sender currentTitle];
Lastly I read a lot but could not understand. In one sentence what is the difference between NSString and UILabel?
(UIButton*)sender means that the sender is passed in the parameter of the method, and that sender is casted to a UIBUtton object.
Because *digit is a pointer to an object, so that will print the memory address of the object
You use it if you want to access the variable trough the getter, and not directly the instance variable.
Is the same, is just a convention, use . to access properties and space to access methods.
NSString represents a string object like "ABC", UILabel is a view that will be displayed in your screen, and which text is a NSString.
I won't go into more details, as SO is not a tutorial page. You'll find all this answers in the first chapter of any CocoaTouch programming book.
(UIButton *) is a typecast to a UIButton object. If you are sure that the sender is a UIButton you can add the typecast. In that way you can directly access the properties/methos on the UIButton object
2.
As far as I understand digit refers to the string object. And *digit means the first (located at index 0).
3.
self means the class it self i.e. calculatorViewController
4.
text is a property of UILabel component
5.
You cannot display a NSString on the display itself you need a UILabel component. You can set the text property to a NSString object and display it on the screen
regards
Johan
i have problems with a really basic thing. setting properties after instantiation a UIViewController-
header.h
IBOutlet UITextField *actionLocationFld;
#property (nonatomic, retain) IBOutlet UITextField *actionLocationFld;
main.h
#synthesize actionLocationFld;
(void)loadSocialActionView:(id)sender
{
self.socialActionView = [[SocialActionViewController alloc] init];
self.socialActionView.actionLocationFld.text = #"test";
[self.view addSubview:self.socialActionView.view];
}
actionLocationFld is a UITextfield. i try to set the text value after instantiation but it does not work. it looks so easy but i can´t figure out. what do i wrong?
any suggestions?
This may happen because actionLocationFld isn't initialized.
Try to call functions in this order:
self.socialActionView = [[SocialActionViewController alloc] init];
[self.view addSubview:self.socialActionView.view];
self.socialActionView.actionLocationFld.text = #"test";
i´ve solved it not by adding another property and passing it the value. it seems it is not possible to access the text property of an UITextfield by the way i tried. here´s the new code line
self.socialActionView.address = #"test";
inside of my viewcontroller i pass the value forward to self.view.actionLocationFld.text
I want to store a list of data records in a NSMutableArray for use in a UITableView. In other languages I would have used a simple 'type' structure to define the record structure but I understand the way to do this in Obj-C is to define a new class. I've done this as follows :
#interface CustSuppListItem : NSObject
#property (nonatomic, copy, readwrite) NSString *acCode;
#property (nonatomic, copy, readwrite) NSString *acCompany;
#property (nonatomic, copy, readwrite) NSString *acContact;
#property (nonatomic, assign, readwrite) double osBalBase;
#property (nonatomic, assign, readwrite) unsigned int acAccStatus;
#end
#implementation CustSuppListItem
#synthesize acCode, acCompany, acContact, osBalBase, acAccStatus;
#end
In the viewDidLoad of my UITableViewController I instantiate the array :
tableListDataArray = [[NSMutableArray alloc] init];
Once I have retrieved my data, I add it to the array as follows :
CustSuppListItem *custSuppItem = [[CustSuppListItem alloc] init];
[custSuppItem setAcCode:[jsonCustSuppRecord getStringForKey:#"acCode"]];
[custSuppItem setAcCompany:[jsonCustSuppRecord getStringForKey:#"acCompany"]];
[custSuppItem setAcContact:[jsonCustSuppRecord getStringForKey:#"acContact"]];
[custSuppItem setOsBalBase:[jsonCustSuppRecord getDoubleForKey:#"osBalBase"]];
[custSuppItem setAcAccStatus:[jsonCustSuppRecord getIntForKey:#"acAccStatus"]];
[tableListDataArray addObject:custSuppItem];
[custSuppItem release];
In my table cellForRowAtIndexPath method, I retrieve the data for the current cell as follows:
CustSuppListItem *listDataRecord = [tableListDataArray objectAtIndex:indexPath.row];
[cell.lblCompanyName setText:listDataRecord.acCompany]; // EXC_BAD_ACCESS here
[cell.lblAcCodeContact setText:[NSString stringWithFormat:#"%#, %#",
listDataRecord.acCode, listDataRecord.acContact]];
[cell.lblBalance setText:[Utils fmtNumber:listDataRecord.osBalBase withDecPlaces:2]];
[cell.lblStatus setText:[Utils exchAccStatusDesc:listDataRecord.acAccStatus]];
return cell;
In the dealloc method for the view controller I release the NSMutableArray :
[tableListDataArray release];
I'm very new to Obj-C so it would be great if somebody could confirm everything I've done so far makes sense and is in order. I am getting an intermittent EXC_BAD_ACCESS error when trying to read the acCompany property (see comment next to line) so something must not be right.
Any help appreciated,
Jonathan
All your code looks reasonable and correct to me at first glance.
A few things that I would look at are:
Confirm that cell definitely has a property lblCompanyName. If you're trying to assign to a property that doesn't exist then you will get this type of error. Have you defined a custom cell object type?
Confirm that it is always the acCompany property that is causing the EXC_BAD_ACCESS, and not just any property on the object. One way to do this would be to change the ordering of the lines in the cellForRowAtIndexPath method.
Confirm that the listDataRecord that's causing the crash is getting populated correctly in the first place. In other words, confirm that your jsonCustSuppRecord is always valid. What does jsonCustSuppRecord getStringForKey: return if the key doesn't exist in the jsonCustSuppRecord?
Set a breakpoint at this line: [tableListDataArray addObject:custSuppItem]; and examine the contents of the custSuppItem each time (this is an extension of point 3. above)
I'm learning Objective-C right now and in order to practice I wrote a simple random maze generator for OS X, which works fine. Next I tried to add some more interaction with buttons, but I'm having trouble with the instance variables as they don't retain the value I assign them. I have come across multiple questions about the same problem, but the solutions to those haven't solved my problem. I also tested if the same problem persists in a simplified version of the program, which it does.
I guess I'm doing something wrong, but I don't know what. Here's what I did:
Created a new project
Added a subclass of NSView called "TestClass"
Added a view with class TestClass in the window in MainMenu.xib
Added an object for TestClass in MainMenu.xib
Added a button to the view and set its tag to 1
Added the following code to TestClass.h and TestClass.m and connected the button to it:
TestClass.h:
#import
#interface TestClass : NSView
{
NSNumber *number;
NSButton *test;
}
#property (nonatomic, retain) NSNumber *number;
#property (assign) IBOutlet NSButton *test;
- (IBAction)testing:(id)sender;
#end
TestClass.m:
#import "TestClass.h"
#implementation TestClass
#synthesize number;
#synthesize test;
- (id)initWithFrame:(NSRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code here.
}
return self;
}
- (IBAction)testing:(id)sender
{
self.number = [[NSNumber numberWithLong:[sender tag]] retain];
}
- (void) drawRect:(NSRect)dirtyRect
{
NSLog(#"%#", number);
}
#end
Whenever I press the button, NSLog just returns null several times.
I normally figure out everything by myself (eventually...), but this time it's really driving me insane, so is there anyone who can help me?
Put the NSLog in testing:, or just put a breakpoint there and see what's stored in number.
Note that self.number = [[NSNumber numberWithLong:[sender tag]] retain]; is double-retaining the NSNumber object (which is wrong), but that shouldn't cause any immediate error.