iOS：不包含nib文件的情况下加载第二个视图控制器

Question

我有一个项目，该项目由标准AppDelegate和ViewController文件组成，但没有使用nib文件。

这是代码：

委托头

// AppDelegate.h
#import <UIKit/UIKit.h>
@class ViewController;
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) ViewController *vc1;
@end

委托执行

// AppDelegate.m
#import "AppDelegate.h"
#import "ViewController.h"

@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.vc1 = [[ViewController alloc] init];
    self.window.rootViewController = self.vc1;
    [self.window makeKeyAndVisible];
    return YES;
}
@end

查看控制器头

//  ViewController.h
#import <UIKit/UIKit.h>

@interface view1 : UIViewController{
    UIButton *button;
}
@end

查看控制器的实现

//  ViewController.m
#import "ViewController.h"

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    CGRect buttonFrame = CGRectMake(30, 30, 100, 30);
    button = [[UIButton alloc] initWithFrame: buttonFrame];
    [button setTitle: @"Switch View" forState: UIControlStateNormal];
    [self.view addSubview: button];

    [button addTarget: self action: @selector(buttonClicked:) forControlEvents: UIControlEventTouchDown];
}

- (void) buttonClicked: (id)sender {
    SecondViewController *vc2 = [[SecondViewController alloc] init];
        //both methods throw the same error - no known class method for selector
    //[self presentViewController:vc2 animated:YES completion:nil];         
    [self presentModalViewController:vc2 animated:YES completion:nil];
}

@end

当试图加载另一个nib稀少view controller （在上面的方法buttonClicked），它保持引发错误

选择器'presentViewController'的未知类方法

我究竟做错了什么？

Answer 1

正确的方法如下：

[self presentViewController:vc2 animated: YES completion:nil];