@end missing in implementation context [closed]

Answer 1

At the end of @implementation ViewController you need @end

Your .m should look like this:

@interface ViewController ()
@end

@implementation ViewController

- (void)viewDidLoad {
    mainInt = 0;
    randomMain = [NSTimer scheduledTimerWithTimeInterval:(1.0/1.0) target:self selector:@selector(randomMainvoid) userInfo:nil repeats:YES];
}


- (void)randomMainvoid {
    mainInt +=1;
    label.text = [NSString stringWithFormat:@"%d", mainInt];       
}    


- (IBAction)Start {
    [startButton setHidden:YES];
    timer = [NSTimer scheduledTimerWithTimeInterval:(0.0088) target:self selector:@selector(onTimer) userInfo:nil repeats:YES];
    pos = CGPointMake(5.0, 6.0);
}

@end

Answer 2

After

- (IBAction)Start {
    [startButton setHidden:YES];
    timer = [NSTimer scheduledTimerWithTimeInterval:(0.0088) target:self selector:@selector(onTimer) userInfo:nil repeats:YES];
    pos = CGPointMake(5.0, 6.0);
}

add @end