UIStoryboard类介绍（如何从Storyboard中加载View Controller）

如何从Storyboard中加载View Controller?

1. 首先了解下UIStoryboard类：

@class UIViewController;

@interface UIStoryboard : NSObject {
}

+ (UIStoryboard *)storyboardWithName:(NSString *)name bundle:(nullable NSBundle *)storyboardBundleOrNil;

- (UIViewController *)instantiateInitialViewController;

- (UIViewController *)instantiateViewControllerWithIdentifier:(NSString *)identifier;

@end

2. 从Storyboard中加载View Controller的方法：

//获取storyboard
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];

//实例化箭头指向的ViewController
    ViewController *rootVC = [storyboard instantiateInitialViewController];  

//根据storyboard ID实例化其中的ViewController
//    ViewController *rootVC = [storyboard instantiateViewControllerWithIdentifier:@"ViewController"];