How to set alpha of static UITableViewCell on startup? - ios

Question

I'm making an application, which has a Settings page. For the Settings page, I am using a UITableViewController with static UITableViewCells. I am using NSUserDefaults to store the settings.
Now, this is the Settings View Controller :
According to the code in the viewDidLoad function in the SettingsTableViewController.m, there is supposed to be a check on the saved setting, and depending on that, the alpha property of the Notification Interval cell is supposed to change. This works fine if I do it in the tableView:didSelectRowAtIndexPath method, however, it is not working in the viewDidLoad method. Here's the source :
#import "SettingsTableViewController.h"
#interface SettingsTableViewController ()
#end
#implementation SettingsTableViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
// Check if setting is already saved.
if ([defaults stringForKey:#"notification"]) {
self.notificationTableViewCell.detailTextLabel.text = [defaults stringForKey:#"notification"];
// Disable the interval cell, if the notifications are turned off.
if([[defaults stringForKey:#"notification"] isEqualToString:#"Off"]) {
self.intervalTableViewCell.alpha = 0.439216f;
self.intervalTableViewCell.userInteractionEnabled = NO;
}
} else {
// If no setting is saved, reset to default settings.
self.notificationTableViewCell.detailTextLabel.text = #"On";
[defaults setObject:#"On" forKey:#"notification"];
[defaults synchronize];
}
// Check if setting is already saved.
if([defaults stringForKey:#"interval"]) {
self.intervalTableViewCell.detailTextLabel.text = [defaults stringForKey:#"interval"];
} else {
// If no setting is saved, reset to default settings.
self.intervalTableViewCell.detailTextLabel.text = #"5 min";
[defaults setObject:#"5 min" forKey:#"interval"];
[defaults synchronize];
}
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Get selected cell.
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
// Reset the state of the cell.
[self.tableView deselectRowAtIndexPath:indexPath animated:YES];
if(cell == self.notificationTableViewCell) {
if([cell.detailTextLabel.text isEqual: #"On"]) {
cell.detailTextLabel.text = #"Off";
[[NSUserDefaults standardUserDefaults] setObject:#"Off" forKey:#"notification"];
self.intervalTableViewCell.alpha = 0.439216f;
self.intervalTableViewCell.userInteractionEnabled = NO;
} else {
cell.detailTextLabel.text = #"On";
[[NSUserDefaults standardUserDefaults] setObject:#"On" forKey:#"notification"];
self.intervalTableViewCell.alpha = 1.0f;
self.intervalTableViewCell.userInteractionEnabled = YES;
}
} else if(cell == self.intervalTableViewCell) {
NSArray *possibleTimes = #[#"1 min", #"5 min", #"10 min", #"30 min"];
int indexOfCurrent = 0;
for (int i = 0; i < possibleTimes.count; i++) {
if([self.intervalTableViewCell.detailTextLabel.text isEqualToString:possibleTimes[i]]) {
indexOfCurrent = i;
}
}
// Return to the starting value of the array.
if(++indexOfCurrent == possibleTimes.count) {
indexOfCurrent = 0;
}
self.intervalTableViewCell.detailTextLabel.text = possibleTimes[indexOfCurrent];
[[NSUserDefaults standardUserDefaults] setObject:possibleTimes[indexOfCurrent] forKey:#"interval"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
}
- (BOOL)prefersStatusBarHidden {
return YES;
}
#end

Answer 1

First of as NSString comparation method you should use this:
isEqualToString:
instead of
isEqualToString:
Second thing is the way you find if selected cell is the one you want to check is not the best idea, I mean this:
if(cell == self.notificationTableViewCell)
Don't do that - you will find yourself in a huge troubles pretty quickly.
Proper way of handling that is to use enumerations, and switch case based on indexPath section, row values. Otherwise you keep a reference to a memory where cell is, but this cell is gonna be reused, by queuing mechanism of UITableView, for a different row - so you're gonna end up keeping some random reference to random cells at the end here.
For the alpha problem I think you should reload table data after you synchronize NSUserDefaults inside didSelectRowAtIndexPath method.
Use reloadData method from UITableView, or even better reload only the section you know that's gonna change on click (optimized version, but you can start with reloading whole table).

Answer 2

Move the code that changes the alpha property of the cell into a method that occurs later in the view lifecycle. A good one to try would be viewWillAppear:.