get NSString from UITextField - objective-c

Question

I'm trying to write a little weightwatchers points calculator app for myself. I know you can just download one from the appstore but i am trying to learn objective-c and thought this would be a fairly easy first app. I just want to use text entered into a textbox and save it as a variable and use said variable to perform basic math with the intValues. I've tried using the 'text' property of UITextField with no luck, could someone help and tell me what i've done wrong here? well this is awkward...it seems i forgot to tell you what the problem is. i've included the errors i'm receiving on their corresponding lines. What i'm getting out of these errors is that i shouldn't be using the "NSString" to define my variables, maybe "int" instead?
.h file:
#import <UIKit/UIKit.h>
#class FirstViewController;
NSString*txtProtein = nil;
NSString *txtCarbs = nil;
NSString *txtFat = nil;
NSString *txtFiber = nil;
NSString *txtPoints = nil;
NSString *txtproteinCalc = nil;
NSString *txtcarbCalc = nil;
NSString *txtfatCalc = nil;
NSString *txtfiberCalc = nil;
#interface AppDelegate : NSObject
<UIApplicationDelegate> {
UIWindow *window;
FirstViewController
*viewController;
UITextField *protein;
UITextField *carbs;
UITextField *fat;
UITextField *fiber;
UITextView *points;
}
#property (nonatomic, retain)
IBOutlet UIWindow *window;
#property (nonatomic, retain)
IBOutlet FirstViewController *viewController;
#end
and the .m file:
#import "FirstViewController.h"
#import "AppDelegate.h"
#implementation AppDelegate
#synthesize window;
#synthesize viewController;
#pragma mark -
#pragma mark Application lifecycle
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//Here is where all of the textboxes are defined.
//All of the strings are in the viewController.h
//This is the protein part
txtProtein = [[[UITextField alloc] initWithFrame:CGRectMake(10.0, 10.0, 50.0, 25.0)]; (expected identifier)
txtProtein.backgroundColor = [UIColor whiteColor]; (property "backgroundcolor" not found on object of type 'NSString')
txtProtein.placeholder = #"Protein"; (property "placeholder" not found on object of type 'NSString')
[viewController.view addSubview:txtProtein]; (property 'view' can not be found in forward class object "FirstViewController")
//This is the carbs part
txtCarbs = [[[UITextField alloc] initWithFrame:CGRectMake(30.0, 10.0, 50.0, 25.0)];
txtCarbs.backgroundColor = [UIColor whiteColor];
txtCarbs.placeholder = #"Carbs";
[viewController.view addSubview:txtCarbs];
//This is the Fat part
txtFat = [[[UITextField alloc] initWithFrame:CGRectMake(50.0, 10.0, 50.0, 25.0)];
txtFat.backgroundColor = [UIColor whiteColor];
txtFat.placeholder = #"Fat";
[viewController.view addSubview:txtFat];
//This is the Fiber
txtFiber = [[[UITextField alloc] initWithFrame:CGRectMake(70.0, 10.0, 50.0, 25.0)];
txtFiber.backgroundColor = [UIColor whiteColor];
txtFiber.placeholder = #"Fiber";
[viewController.view addSubview:txtFiber];
//Total Points
txtPoints = [[[UITextField alloc] initWithFrame: CGRectMake(150.0, 10.0, 50.0, 25.0)]autorelease];
txtPoints.backgroundColor = [UIColor greenColor];
txtPoints.editable = NO;
[viewController.view addSubview:txtPoints];
//Protein divided by 10.9375
txtproteinCalc = [txtProtein.text intValue] / [10.9375];
//Carbs divided by 9.2105
txtcarbCalc = [txtCarbs.text intValue] / [9.2105];
//Fat divided by 3.8889
txtfatCalc = [txtFat.text intValue] / [3.8889];
//Fiber divided by 12.5
txtfiberCalc = [txtFiber.text intValue] / [12.5];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(calculatePoints)
name:UITextFieldTextDidChangeNotification
object:nil];
//Add the view controller's view to the window and display
[self.window addSubview:viewController.view];
[self.window makeKeyAndVisible];
//Make keyboard show up in the Protein (The first) box
[txtProtein becomeFirstResponder];
return YES;
}
#pragma mark -
#pragma mark Memory management
- (void)applicationDidReceiveMemoryWarning:(UIApplication *)application {
/*
Free up as much Memory as possible by purging cached data objects that can be recreated (or reloaded from disk) later/
*/
}
-(void)dealloc {
[txtProtein release];
[txtFiber release];
[txtFat release];
[txtCarbs release];
[txtPoints release];
[viewController release];
[window release];
[super dealloc];
}
#pragma mark -
#pragma mark Other Methods
-(void)calculatePoints {
NSLog(#"Calculating FoodTrakr Value...");
txtPoints.text = #"";
if (txtProtein.text.length > 0 && [txtProtein.text intValue]>0 && txtFiber.text.length >0 && [txtFiber.text intValue]>0 && txtFat.text.length >0 && [txtFat.text intValue]>0 && txtCarbs.text.length >0 && [txtCarbs.text intValue]>0
)
{
int Points = [txtproteinCalc.text intValue] + [txtcarbCalc.text intValue] + [txtfatCalc.text intValue] - [txtfiberCalc.text intValue];
txtPoints.text = [[NSNumber numberWithInt:points] stringValue];
}
}
#end
Thanks in advance for any help!
also, if you guys have any recommended books for learning objective c, i've done some reading but i know i obviously need to read up some more, if you could leave any suggestions that helped you learn that would be awesome. Thanks!

Answer 1

To be blunt, the posted code has a lot of serious issues. Let's start with the immediate compile errors.
You have:
txtProtein = [[[UITextField alloc] initWithFrame:CGRectMake(10.0, 10.0, 50.0, 25.0)]; (expected identifier)
txtProtein.backgroundColor = [UIColor whiteColor]; (property "backgroundcolor" not found on object of type 'NSString')
txtProtein.placeholder = #"Protein"; (property "placeholder" not found on object of type 'NSString')
[viewController.view addSubview:txtProtein]; (property 'view' can not be found in forward class object "FirstViewController")
The first line has one too many open brackets. The other major problem with this is you are creating a UITextField but you are assigning it to a variable for an NSString. Instead of txtProtein you should use your protein variable which has the property type. So the code should be:
protein = [[UITextField alloc] initWithFrame:CGRectMake(10.0, 10.0, 50.0, 25.0)];
protein.backgroundColor = [UIColor whiteColor];
protein.placeholder = #"Protein";
[viewController.view addSubview:protein];
You have the same issues repeated over and over in this code.
The next big issue is why is all of this code in your app delegate? Most, if not all, of this code belongs in the FirstViewController.m file. Your app delegate should not be responsible for setting up the view controller. Let the view controller set itself up.
Next, why do you have all of these global variables?
I suggest you find some good tutorials on Objective-C programming then some good tutorials on iOS app development.