How to check the latest version of the app with NSUserDefaults - objective-c

Question

I want to check if user is using the latest version of the app. If so, i should color the background of some cells.
This is the code i'm using:
appDelegate.m
NSString *lastVersion = [[NSUserDefaults standardUserDefaults] objectForKey:#"lastVer"];
method where i want to check:
NSString *lastVersion = (NSString *) [[NSUserDefaults standardUserDefaults] objectForKey:#"lastVer"];
NSString *version = [[[NSBundle mainBundle] infoDictionary] objectForKey:#"CFBundleVersion"];
lastVersion = #"1.3.4";
if(![lastVersion isEqualToString:version]){
cell.backgroundColor = [UIColor yellowColor]; ;
cell.imageView.image = [UIImage imageNamed:#"image.png"];
}
else {
cell.imageView.image = nil;
cell.backgroundColor = [UIColor whiteColor];
}
}
Am i doing it right? Is my code checking for the latest version or? How can i simulate this behavior in the simulator \ on device?
What i want to do is check if the user is using the latest version of the app, in order to call in another NSUserDefaults key to show the cells of my tableView with a different background color.
EDIT
Code i'm using to change the cells background if the user is using the latest version of my app and if the user has used the app less than three times:
NSString *cellValue = cell.textLabel.text;
NSNumber *runNumber = (NSNumber *)[[NSUserDefaults standardUserDefaults] objectForKey:#"runNum"];
NSString *lastVersion = [[NSUserDefaults standardUserDefaults] objectForKey:#"lastVer"];
NSString *version = [[[NSBundle mainBundle] infoDictionary] objectForKey:#"CFBundleVersion"];
if (!runNumber) {
runNumber = [NSNumber numberWithInt:0];
[[NSUserDefaults standardUserDefaults] setObject:runNumber forKey:#"runNum"];
[[NSUserDefaults standardUserDefaults] synchronize];
}
if([lastVersion isEqualToString:version]){ //check if the user is using the latest version
if ([runNumber intValue] < 4) { //check if user has used the app less than 3 times
if ([cellValue isEqual: "someText"] ){
cell.backgroundColor = [UIColor yellowColor]; ;
cell.imageView.image = [UIImage imageNamed:#"image.png"];
}
else {
cell.imageView.image = nil;
cell.backgroundColor = [UIColor whiteColor];
}
}
else {
cell.imageView.image = nil;
cell.backgroundColor = [UIColor whiteColor];
}
}
}

Answer 1

this code will not set anything..
NSString *lastVersion = [[NSUserDefaults standardUserDefaults] objectForKey:#"lastVer"];
lastVersion = #"1.3.4";
you need a setter:
[[NSUserDefaults standardUserDefaults] setObject: #"1.3.4" forKey:#"lastVer"];//in memory
[[NSUserDefaults standardUserDefaults] synchronize];//to disk
and a getter:
NSString *lastVersion = [[NSUserDefaults standardUserDefaults] objectForKey:#"lastVer"];
edit:
remember that lastVersion is a pointer and you just set it to point somewhere else, that doesn't set it in stdUserDefaults and it doesn't synchronize it to disk.

Answer 2

Surely if you want to check if the user is using the latest version of the app you would need to check with an external resource.
e.g.
Simple HTTP request to your own server, which returns your latest app version.
Then compare this against your current version [[[NSBundle mainBundle] infoDictionary] objectForKey:#"CFBundleVersion"];
Store the result of this test in NSUserDefaults