Setting the view programmatically

Question

I am trying to set my project without using storyboards in xcode and with objective c.

My appDelegate:

.h

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

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

.m

#import "AppDelegate.h"

@interface AppDelegate ()

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    ViewController *vc = [[ViewController alloc] init];
    self.window.rootViewController = vc;
    return YES;
}

etc...

My viewController file:

.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIView *view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    view.backgroundColor = [UIColor redColor];
    [self.view addSubview:view];

}

I think my code is right and we should have a red screen when I run it, but I only get a black screen. Can someone tell me if I have forgotten something or is it something to do with the project settings. Thanks.

I didn't know about visual debugger but I am reading about it now. I have, however, just added an NSLog to my viewDidLoad and it doesn't get called. Why is this? I thought the line: 'self.window.rootViewController = vc;' automatically called said method?? tx — Paul, Jul 08 '16 at 12:33

score 1 · Answer 1 · edited Jul 08 '16 at 12:28

1

Add

self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];

to your application:didFinishLaunchingWithOptions:

edited Jul 08 '16 at 12:28

nhgrif

61,578
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answered Jul 08 '16 at 12:27

iosp

111
5

score 0 · Accepted Answer · answered Jul 08 '16 at 12:32

You are missing two steps.

Initialize the window:

self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];

Make the window key & visible:
```
[self.window makeKeyAndVisible];
```

So all together, your code should look like this:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    // Initialize the window
    self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds]; 

    // Add the view controller to the window
    ViewController *vc = [[ViewController alloc] init];
    self.window.rootViewController = vc;

    // Make window key & visible
    [self.window makeKeyAndVisible];

    return YES;
}

Setting the view programmatically

2 Answers2