[iPhone] Storyboard を使わずに画面遷移 (Objective-C)

色々な制約があって、Storyboard を使わずにラベルを貼ったり、ボタンを設定することがあります
画面遷移をコードだけで実行させるにはどうするか試してみました。
　

Objective-C
Xcode 9.3.1

presentViewController

遷移先の SecondViewControlle のインスタンスを生成して、presentViewControllerで遷移させます。
これはStoryboardを使った時の選択肢の１つであるPresent modallyに相当し、
「現在のviewの上に覆いかぶさるように新しいviewを表示」させる画面遷移となります。
SwiftでSegueを使った例：

[iPhone] Segueで画面遷移させる

アプリでA画面からB画面に遷移したいケースは結構あります。コードで記述せざる得ない場合もありますが、StoryboardでSceneを作って...

2020-03-31 12:38

    SecondViewController *secondVC = [[SecondViewController alloc] init];
    [self presentViewController: secondVC animated:YES completion: nil];

1 2	SecondViewController *secondVC = [[SecondViewController alloc] init]; [self presentViewController: secondVC animated:YES completion: nil];

　
ラベルやボタンも全て
Storyboard は一切使わずに
コードで記述したケースです
　
ViewController.m

#import "ViewController.h"
#import "SecondViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIColor *customColor = [UIColor colorWithRed:1.0 green:0.8 blue:0.8 alpha:1.0];
    self.view.backgroundColor = customColor;

    UILabel *firstLabel = [[UILabel alloc] init];

    int screenWidth = self.view.frame.size.width;
    int screenHeight = self.view.frame.size.height;

    
    firstLabel.frame = CGRectMake((screenWidth/2 - 150/2), 250, 150, 20);
    firstLabel.text = @"First Screen";
    firstLabel.textAlignment = NSTextAlignmentCenter;
    [self.view addSubview:firstLabel];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake((screenWidth/2 -50), screenHeight/2, 100, 30);
    button.backgroundColor = [UIColor grayColor];
    [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [button setTitle:@"Move Scene" forState:UIControlStateNormal];
    
    [button addTarget:self action:@selector(moveButton:)forControlEvents:UIControlEventTouchDown];
    [self.view addSubview:button];
}

-(void)moveButton:(UIButton*)button{
    SecondViewController *secondVC = [[SecondViewController alloc] init];
    [self presentViewController: secondVC animated:YES completion: nil];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

#import "ViewController.h"

#import "SecondViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

UIColor *customColor = [UIColor colorWithRed:1.0 green:0.8 blue:0.8 alpha:1.0];

self.view.backgroundColor = customColor;

UILabel *firstLabel = [[UILabel alloc] init];

int screenWidth = self.view.frame.size.width;

int screenHeight = self.view.frame.size.height;

firstLabel.frame = CGRectMake((screenWidth/2 - 150/2), 250, 150, 20);

firstLabel.text = @"First Screen";

firstLabel.textAlignment = NSTextAlignmentCenter;

[self.view addSubview:firstLabel];

UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];

button.frame = CGRectMake((screenWidth/2 -50), screenHeight/2, 100, 30);

button.backgroundColor = [UIColor grayColor];

[button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];

[button setTitle:@"Move Scene" forState:UIControlStateNormal];

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

[self.view addSubview:button];

}

-(void)moveButton:(UIButton*)button{

SecondViewController *secondVC = [[SecondViewController alloc] init];

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

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

　
遷移先
SecondViewController.m

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    }
    return self;
}

- (void)loadView
{
    [super loadView];
    UIColor *customColor = [UIColor colorWithRed:0.8 green:0.9 blue:1.0 alpha:1.0];
    self.view.backgroundColor = customColor;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    UILabel *secondLabel = [[UILabel alloc] init];
    int screenWidth = self.view.frame.size.width;
    
    secondLabel.frame = CGRectMake((screenWidth/2 - 150/2), 250, 150, 20);
    secondLabel.text = @"Second Screen";
    secondLabel.textAlignment = NSTextAlignmentCenter;
    
    secondLabel.textColor = [UIColor blueColor];
    [self.view addSubview:secondLabel];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

}

return self;

}

- (void)loadView

{

[super loadView];

UIColor *customColor = [UIColor colorWithRed:0.8 green:0.9 blue:1.0 alpha:1.0];

self.view.backgroundColor = customColor;

}

- (void)viewDidLoad {

[super viewDidLoad];

UILabel *secondLabel = [[UILabel alloc] init];

int screenWidth = self.view.frame.size.width;

secondLabel.frame = CGRectMake((screenWidth/2 - 150/2), 250, 150, 20);

secondLabel.text = @"Second Screen";

secondLabel.textAlignment = NSTextAlignmentCenter;

secondLabel.textColor = [UIColor blueColor];

[self.view addSubview:secondLabel];

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

　
ヘッダーファイルはそのままです。

Ref: presentViewController:animated:completion: – UIViewController …