ios - 如何在实例化之前检查 Storyboard中 Controller 的存在？

Question

通过代码使用 storoboard 时，我们可以通过标识符实例化 Controller ，但是如果找不到具有此标识符的 Controller ，则会崩溃。如何避免崩溃和/或提前检查 Controller 的存在？

Controller 实例化示例:

UIViewController *controller = [[UIStoryboard storyboardWithName:@"Settings" bundle:nil] instantiateViewControllerWithIdentifier:model.identifier];
[self.navigationController pushViewController:controller animated:YES];

Answer 1

试试这个。可能不是您正在寻找的。它是一种解决方法。

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad 
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    _story = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];
}

- (IBAction)go:(id)sender 
{
    SecondViewController *second;

    @try {
        second = [_story instantiateViewControllerWithIdentifier:@"Hello"];
    }
    @catch (NSException *exception) {
        NSLog(@"Reason %@" , exception.reason);
    }
    @finally {
        if (second == nil) {
            NSLog(@"VC %@" , second);
        }
    }


}
@end