Why isn't my UILabel getting set? [closed] - ios

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I have been stuck on a problem for hours now, and can not seem to figure this out. I am new to Objective-C and it is really annoying me that I can not get this. I am trying to get the NSLog values displayed in bmiLabel, but my bmiLabel always shows NULL.
This is my code:
ViewController.h:
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController<UITextFieldDelegate>
#property (strong, nonatomic) IBOutlet UITextField *num1;
#property (strong, nonatomic) IBOutlet UITextField *num2;
#property (strong, nonatomic) IBOutlet UILabel *resultLabel;
#property (strong, nonatomic) IBOutlet UILabel *bmiLabel;
- (IBAction)bmiButton:(id)sender;
#end
ViewController.m:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize num1, num2, resultLabel, bmiLabel;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(BOOL) textFieldShouldReturn:(UITextField *)textField
{
[textField resignFirstResponder];
return YES;
}
- (IBAction)bmiButton:(id)sender
{
float sum = [self.num2.text floatValue] / ([self.num1.text floatValue] *
[self.num1.text floatValue]);
NSString *Output = nil;
Output = [[NSString alloc] initWithFormat:#"%.2f", sum];
self.resultLabel.text = Output;
NSString *mystring;
NSString * bmi = [[NSString alloc] NSStringWithFormat:#"%#", mystring];
self.bmiLabel.text = bmi;
if(sum <= 18.5)
{
NSLog(#"You are underweight", mystring);
}
if(sum <= 18.5)
{
NSLog(#"you are normal");
}
if (sum <= 25.0)
{
NSLog(#"You are overweight");
}
if(sum <= 30)
{
NSLog(#"You are obese");
}
}
#end

Answer 1

Well, trying to be a little psychic, I note that you're not actually putting anything in the BMI case. Try this instead:
- (IBAction)bmiButton:(id)sender {
float sum = [self.num2.text floatValue] / ([self.num1.text floatValue] *
[self.num1.text floatValue]);
NSString *Output = [NSString stringWithFormat:#"%.2f", sum];
self.resultLabel.text = Output;
NSString *mystring= nil;
if (sum <= 18.5) {
mystring = #"You are underweight";
} else if (sum <= 25.0) {
mystring = #"you are normal";
} else if (sum <= 30.0){
mystring = #"You are overweight";
} else {
mystring = #"You are obese:";
}
self.bmiLabel.text = mystring;
}

Answer 2

I think [[NSString alloc] NSStringWithFormat:#"%#", mystring]; code has a problem. Try below code
NSString *mystring;
NSString * bmi = [NSString stringWithFormat:#"%#", mystring];
self.bmiLabel.text = bmi;
Also you must initialize mystring. If you don't mystring always returns null.

Answer 3

This code is not useful because you bmi is going to be an empty string. So bmiLabel will be empty.
NSString *mystring;
NSString * bmi = [[NSString alloc] NSStringWithFormat:#"%#", mystring];
self.bmiLabel.text = bmi;
The rest of your code is fine. Although in my opinion you use too much objects in your code. For example, Your NSString is not necessary, you can write this
float sum = [self.num2.text floatValue] / ([self.num1.text floatValue] *
[self.num1.text floatValue]);
self.resultLabel.text = [[NSString alloc] initWithFormat:#"%.2f", sum];

Answer 4

This:
[[NSString alloc] NSStringWithFormat:#"%#", mystring];
StringWithFormat is a class method which would be sent to the class:
string = [NSString stringWithFormat:#"some string"];
This tells the class to give you a string which is already allocated and initialized.
In your case you should (can) use:
string = [[NSString alloc]initWithFormat:#"some string"];
Also, about this line in your code:
NSString * bmi = [[NSString alloc] NSStringWithFormat:#"%#", mystring];
you could just do this:
[[self bmiLabel]setText:[[NSString alloc]initWithString:mystring]];
or if you prefer dot notation
self.bmiLabel.text = [[NSString alloc]initWithString:mystring]];

Answer 5

I don't know what you're asking, but there is an error here:
NSString *mystring;
NSString * bmi = [[NSString alloc] NSStringWithFormat:#"%#", mystring];
self.bmiLabel.text = bmi;
First off, your string format setters:
[[NSString alloc] NSStringWithFormat:#"someformat: %#", someVariable];
Should be:
[NSString stringWithFormat:#"someformat: %#", someVariable];
If however, those were correct, this would still have this problem:
NSString * bmi = [NSString stringWithFormat:#"%#", mystring];
Is very strange when mystring is already a string. It's equivelant to:
NSString * bmi = mystring;
Basically, those three lines are equivelant to:
NSString * mystring;
self.bmiLabel.text = mystring;
Answer
The problem is, you never assigned a value to mystring