Xcode段控制器错误

Question

I have an issue when I click on the segment controller in the simulator. Here's my code

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UITextField *inputField;

@property (weak, nonatomic) IBOutlet UILabel *outputField;

@property (weak, nonatomic) IBOutlet UISegmentedControl *segmentController;
@end

@implementation ViewController

- (IBAction)updateButton:(id)sender {
    NSMutableString *buf = [NSMutableString new];
    switch (self.segmentController.selectedSegmentIndex) {
        case 0:
            [buf appendString: @"unit two"];
            break;
        case 1:
            [buf appendString: @"unit three"];
            break;
        default:
            [buf appendString: @"unit four"];
            break;
    }
    self.outputField.text = buf;
}

- (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.
}

@end

Here's the error I get:

2016-07-29 17:40:45.506 UnitConverter[3213:534645] -[ViewController segmentController:]: unrecognized selector sent to instance 0x7fae71dbd040 2016-07-29 17:40:45.509 UnitConverter[3213:534645] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ViewController segmentController:]: unrecognized selector sent to instance 0x7fae71dbd040'

Answer 1

It's looking for the method segmentController , but your class doesn't have one. Right click on the Segment Controller in IB and remove and re-add the connection to. You may have more than one Action connected. Click the little X to remove them.

 - (IBAction)updateButton:(id)sender