Filling UITableView using NSUserdefaults - ios

Question

I've been trying for a while now to get the tableview to work correctly. Every day I am making a bit of progress but I am not able to see any kind of feedback by testing the app so I am not sure if I am doing something correctly or not.
I've searched on google for a while, looked at apple docs, but I still don't understand how I can populate the UITableView properly.
First problem. Where do I get the cell? I need to make a custom cell to display the data. The solution seems to be using a nib, but how can I load it on another view controller?
Second problem. This cell should obviously have dynamic content. This content would be picked up from the user defaults (I am able to do that), but I have no idea how I could access the labels in the nibs to achieve this.
Third problem. I want to have different sections (each section has a different kind of cell to display), with different headers/footers. As always, here I find the documentation lacking. How can I achieve this?
Fourth, and most important problem. I have NO IDEA on how to load the cells. Apparently that is done by cellForRowAtIndexPath but I am unsure how it manages to do that.
Finally, here's the code (along with the stacktrace). Hope you can help me. Please, do not close this for duplicate. Firstly, it shouldn't be, secondly, it's not a duplicate if the duplicate question was asked 3+ years ago because of how much the libraries have been updated.
#import "profileViewController.h"
#import "../Objs/CCProfileObject.h"
#interface profileViewController ()
#property (weak, nonatomic) IBOutlet UITableView *tableView;
#property (strong, nonatomic) IBOutlet UITableViewCell *proxySampleCell;
#property (strong, nonatomic) IBOutlet UITableViewCell *ccSampleCell;
#end
#implementation profileViewController
#synthesize tableView;
- (void)viewDidLoad{
// Dark mode, you can skip all of this
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(changeColor:)
name:#"darkToggle" object:nil];
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
if([userDefaults boolForKey:#"darkMode"] == YES){
[self changeColor:nil];
}
}
- (void)viewDidAppear:(BOOL)animated{
// Display profiles
NSData *arrayData = [[NSUserDefaults standardUserDefaults] objectForKey:#"profileArray"];
NSArray *profiles = [NSKeyedUnarchiver unarchiveObjectWithData:arrayData];
for(NSObject *profile in profiles){
if([profile class] == [CCProfileObject class])
{
CCProfileObject *ccProfile = (CCProfileObject*) profile;
printf("%s\n", [ccProfile.getName UTF8String]);
// Retrieve info from the object
// Duplicate cell
// Change appropriate labels
// Add cell to a specific section
}
// Different types of cells will be added later
// Concept is the same, what changes is the specific section and cell to duplicate
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
if(indexPath.section == 1){
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"reusableShippingCell"];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"reusableShippingCell"];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
cell.textLabel.text = #"aldo";
return cell;
}
return nil;
}
// This should be the only part that actually works (I use the same class twice because proxy and shipping are not yet done)
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
// Display profiles
NSData *arrayData = [[NSUserDefaults standardUserDefaults] objectForKey:#"profileArray"];
NSArray *profiles = [NSKeyedUnarchiver unarchiveObjectWithData:arrayData];
NSMutableArray *sectionData = [[NSMutableArray alloc]init];
for(NSObject *profile in profiles){
// Credit
if([profile class] == [CCProfileObject class])
{
[sectionData insertObject:#1 atIndex:0];
}
// Shipping
else if([profile class] == [UIImage class])
{
[sectionData insertObject:#1 atIndex:1];
}
// Proxy
else if([profile class] == [UIImage class])
{
[sectionData insertObject:#1 atIndex:2];
}
}
int toReturn = 0;
for(int i = 0; i < [sectionData count]; i++){
toReturn += [[sectionData objectAtIndex:i] integerValue];
}
return toReturn;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
// Credit card section
if(section == 0){
return 1;
} else if (section == 1){
return 2;
} else {
return 3;
}
}
`Assertion failure in -[UITableView _configureCellForDisplay:forIndexPath:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3698.52.10/UITableView.m:9453
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView (<UITableView: 0x16106d000; frame = (0 0; 375 812); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x1d0243bd0>; layer = <CALayer: 0x1d0030f60>; contentOffset: {0, -88}; contentSize: {375, 117}; adjustedContentInset: {88, 0, 83, 0}>) failed to obtain a cell from its dataSource (<profileViewController: 0x15ff14c70>)
First throw call stack:
(0x1837f6d8c 0x1829b05ec 0x1837f6bf8 0x1841e6fa0 0x18d4975b0 0x18d4941e8 0x18d493e00 0x18d492b1c 0x18d48e668 0x18d3cb770 0x18796d25c 0x1879713ec 0x1878ddaa0 0x1879055d0 0x18d7b56b4 0x18379f2bc 0x18379ea7c 0x18379c7b0 0x1836bcda8 0x18569f020 0x18d69d78c 0x1048a4f90 0x18314dfc0)
libc++abi.dylib: terminating with uncaught exception of type NSException
You are not required to solve all of my problems with a single answer. Even fixing a problem/explaining what I need to do is enough as that will allow me to at least move a bit forward.

Answer 1

First, you don't need a custom nib for UITableViewCell unless you have a really complex cell. Rather than that, you can directly design your cell layout using Prototype Cells in UITableView's Attributes inspector. Just give Prototype Cells a number & design appropriate cell's layout inside UITableView view. Don't forget to set identifier for each of them, that will help you load correct layout in cellForRowAtIndexPath.
For simple cell layout, you can provide each of elements of the cell a tag number. This will help you access them whenever you need them like this:
UILabel *label = [cell viewWithTag:100];
Every UITableView needs a DataSource, you will implement UITableViewDataSource to provide:
Number of sections for your table
Number of items for each section
Content for individual cell
You just did it in your provided source code, except one thing: cellForRowAtIndexPath requires a UITableViewCell to be returned, not nil. If you return nil, exception will be thrown.
So, a working cellForRowAtIndexPath might look like this:
#implementation ViewController {
NSArray *data;
}
- (void)viewDidLoad {
[super viewDidLoad];
// You load your data from NSUserDefault here
data = [self loadDataFromNSUserDefault];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *cellIdentifier = #"defaultCell";
if (indexPath.section == 0) {
cellIdentifier = #"customCell1";
} else if (indexPath.section == 1) {
cellIdentifier = #"customCell2";
}
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
// Access your view's children using their `tag`
UILabel *title = [cell viewWithTag:100];
UIImageView *icon = [cell viewWithTag:101];
// Set content
title.text = [[data objectAtIndex:indexPath.row] objectForKey:#"title"];
icon.image = [UIImage imageNamed:[[data objectAtIndex:indexPath.row] objectForKey:#"icon"]];
return cell;
}

Answer 2

Your core problem lies in this line - if (indexPath.section == 1) - the section numbering starts from 0. So you return nil for cells in your first section (numbered 0), and any section beyond the second one (numbered 1), which causes the crash. You should never return nil from cellForRow.
That being said - I still recommend you read through the links provided in the comments, you may still learn something valuable and/or interesting.