how to update the content in the UIlabel - objective-c

Question

When I use swipe gesture on the screen the label on the screen it didn't update the content and the number stop at 120, after I declare:
#property (weak, nonatomic) UILabel *label;
when I swipe the screen then it appear error on the Xcode,
If someone can help me to solve this problem I will really appreciate it
#interface ViewController ()
{
double numOfSpeed;
}
#property (weak, nonatomic) UILabel *label;
#end
implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
numOfSpeed = 120;
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(200, 300, 100, 100)];
label.text =[NSString stringWithFormat:#"%.0f", numOfSpeed];
label.backgroundColor = UIColor.blueColor;
[self.view addSubview:label];
UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeToControlTheSpeedOfRhythm:)];
UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeToControlTheSpeedOfRhythm:)];
UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeToControlTheSpeedOfRhythm:)];
UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(swipeToControlTheSpeedOfRhythm:)];
[swipeRight setDirection:UISwipeGestureRecognizerDirectionRight];
[swipeLeft setDirection:UISwipeGestureRecognizerDirectionLeft];
[swipeUp setDirection:UISwipeGestureRecognizerDirectionUp];
[swipeDown setDirection:UISwipeGestureRecognizerDirectionDown];
[swipeLeft setNumberOfTouchesRequired:1];
[swipeRight setNumberOfTouchesRequired:1];
[swipeUp setNumberOfTouchesRequired:1];
[swipeDown setNumberOfTouchesRequired:1];
[self.view addGestureRecognizer:swipeLeft];
[self.view addGestureRecognizer:swipeUp];
[self.view addGestureRecognizer:swipeDown];
[self.view addGestureRecognizer:swipeRight];
}
- (void)swipeToControlTheSpeedOfRhythm:(UISwipeGestureRecognizer *)sender
{
NSLog(#"gesture respone");
if(sender.direction == UISwipeGestureRecognizerDirectionLeft)
{
numOfSpeed -= 10;
self.label.text = [NSString stringWithFormat:#"%.0f", numOfSpeed];
NSLog(#"gesture Left respone");
}else if (sender.direction == UISwipeGestureRecognizerDirectionDown){
numOfSpeed -= 10;
self.label.text = [NSString stringWithFormat:#"%.0f", numOfSpeed];
NSLog(#"gesture down respone");
}else if (sender.direction==UISwipeGestureRecognizerDirectionUp){
numOfSpeed += 10;
self.label.text = [NSString stringWithFormat:#"%.0f", numOfSpeed];
NSLog(#"gesture up respone");
}else if(sender.direction==UISwipeGestureRecognizerDirectionRight){
numOfSpeed += 10;
self.label.text = [NSString stringWithFormat:#"%.0f", numOfSpeed];
NSLog(#"gesture right respone");
}
}
#end

Answer 1

You should init your UILabel like this:
self.label = [[UILabel alloc] initWithFrame:CGRectMake(200, 300, 100, 100)];
Then use self.label through all your code. The problem is that your label property is not being assigned inside your viewDidLoad code.
Edit
And use a strong reference in your UILabel property unless you're using #IBOutlets.

Answer 2

Remove "UILabel *" from
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(200, 300, 100, 100)];