CODEWITHSUNDEEP
iosiphoneobjective-cipaduiimageview
M Zubair Shamshad
M Zubair Shamshad

Reputation: 2741

how to set background image properly in iOS

I am working on a view based app, I have set the background image as follows.

.h file:

UIImageView *BackgroundImage;

.m file:

viewdidLoad method:

BackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BG.png"]];
[[self view] addSubview:BackgroundImage];
[BackgroundImage.superview sendSubviewToBack:BackgroundImage];

and on the rotate method:

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation 
{

BackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BG2.png"]];
[[self view] addSubview:BackgroundImage];
[BackgroundImage.superview sendSubviewToBack:BackgroundImage];
[super viewDidLoad];

}

Using this code I am able to set the background, but on rotation the first loaded image is not removed and the second one is loading just behind the first one, so just half of the image is visible, because of the first image is in front of second one.

Is there is a better way to do this?

OR

How can I just remove the first image and then set the second one?

Please help me to resolve this.

Upvotes: 1

Views: 750

Answers (4)

Nikolai Ruhe
Nikolai Ruhe

Reputation: 81856

Just set the new image when rotating:

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation 
{
    BackgroundImage.image = [UIImage imageNamed:@"BG2.png"];
}

Your code kept adding new image views when rotating.

How [do stuff] properly in iOS?

  • Start your ivar names using an underscore and a lowercase letter: _backgroundImage instead of BackgroundImage.
  • Insert a subview in the right spot: [self.view insertSubview:_backgroundImage atIndex:0];

Upvotes: 0

Fran Martin
Fran Martin

Reputation: 2369

If you change your code like this should to work

BackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BG.png"]];
[self.view addSubview:BackgroundImage];
[self.view sendSubviewToBack:BackgroundImage];

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation 
{

     [BackgroundImage removeFromSuperview];
     BackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BG2.png"]];
     [self.view addSubview:BackgroundImage];
     [self.view sendSubviewToBack:BackgroundImage];
     [super viewDidLoad];

 }

Upvotes: 1

Himanshu Joshi
Himanshu Joshi

Reputation: 3399

This is because you are initializing the UIImageview again. Better to use same UIImageView that is backgroundImage with different image.

[Background Image set image:[UIImage imageNamed:@"BG2.png"]];

Upvotes: 0

The dude
The dude

Reputation: 7924

Change your didRotate... method to:

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation 
{
    [BackgroundImage removeFromSuperview];
    BackgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BG2.png"]];
    [[self view] addSubview:BackgroundImage];   
}

Notice the [BackgroundImage removeFromSuperview]; line. What we are doing here is whenever the device rotates, you remove the old image view and add another one.

Also please notice that variable names should start with lower case, so BackgroundImage should be backgroundImage. This is to tell them apart from classes' names.

Upvotes: 2

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