UIPicker sizing in landscape mode

问题:

I am trying to develop an app with a UIPicker in landscape mode, taking up (almost) the entire width of the screen (with 5 or 6 components). Can you please tell me how to set the size of UIPicker. Thank you very much for your help.

回答1:

Actually, I resize my pickers for almost every app. I do not like that they take up the entire screen. Here is the method that I am using: (note that I am also rotating the picker to be horizontal)

in viewDidLoad .....

picker = [[UIPickerView alloc] initWithFrame:CGRectZero];
picker.delegate = self;
picker.dataSource = self;
picker.showsSelectionIndicator = NO;


//Resize the picker, rotate it so that it is horizontal and set its position
CGAffineTransform rotate = CGAffineTransformMakeRotation(-1.57);  
rotate = CGAffineTransformScale(rotate, .46, 2.25);
CGAffineTransform t0 = CGAffineTransformMakeTranslation(3, 22.5);
picker.transform = CGAffineTransformConcat(rotate,t0);
[self.view addSubview:picker];
[picker release];

Then, I like to add a background image for my view that covers up the grey bars (which are now on the top and bottom) of the UIPicker:

//Create the overlay to superimpose ontop of the picker
//In this case, the image is the size of the screen with a transparent area the size of the //UIPickerView cut out in the middle

UIImageView *uiiv = [[UIImageView alloc] 
                     initWithImage:[UIImage                                 imageNamed:@"problem_bg.png"]];
uiiv.userInteractionEnabled = NO;
uiiv.opaque = YES; //for performance
[self.view addSubview:uiiv];
[uiiv release];

UIPickerView delegate method:

-(UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)rowforComponent:(NSInteger)component reusingView:(UIView *)view
 {

    UIView *viewForRow = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 280)] autorelease];
    UIImageView *img = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"myimage.png"]];

    img.frame = CGRectMake(0, 0, 102,280);
    img.opaque = YES;
    [viewForRow addSubview:img];
    [img release];
    UILabel *label;

    UIFont *font = [ UIFont fontWithName:@"Helvetica"  size:20];

    label = [[[UILabel alloc] initWithFrame:CGRectMake(10, 20, 270, 100)] autorelease];

    label.text = @"I am a label";
    label.textAlignment = UITextAlignmentCenter;
    label.textColor = [UIColor blackColor];
    label.font = font;
    label.backgroundColor = [UIColor clearColor];
    label.opaque = NO;
        [viewForRow addSubview:label];

    CGAffineTransform rotate = CGAffineTransformMakeRotation(1.57);  
        [viewForRow setTransform:rotate]; 
    return viewForRow;

}

This gives a much smaller, horizontal picker with a nice look and feel. I hope this helps someone.

回答2:

You can edit the size by opening the .xib file in TextEdit and changing the size of the UIPickerView.

回答3:

You can't. UIPickerView's size is constant.

UPDATE: It turns out you can resize an UIPickerView. The trick is to place it inside another (smaller) UIView, and resize that view. I haven't tried this yet.

UPDATE 2: This method does not resize the UIPickerView, but rather crops it. It might or might not be what you're looking for, but AFAIK, there's no way to truly resize an UIPickerView, and this is as close as it gets. It doesn't look that bad.

UPDATE 3 (Long overdue): As of SDK 3.0, UIPickerView is completely resizeable using initWithFrame or setFrame.

回答4:

I wrestled with the same issue of resizing the pickerview. After some research and headache here is something you can easily do:

1. Forget Interface builder! I think you can so much better UI without the interface builder.

2. In your controllers overwrite the load view method.

   -(void)loadView
   {
           //create your view
    self.view = [[UIView alloc] initWithFrame:CGRectZero];
    // create a default sized pickerView
    pickerView = [[UIPickerView alloc] initWithFrame:CGRectZero];
    pickerView.delegate = self;
    pickerView.dataSource = self;
    pickerView.showsSelectionIndicator = YES;
   
     // Get its frame
    CGRect pickerFrame = pickerView.frame;
   
      // Set it to what ever you like, I use a default screen height times a shrink factor like 0.75 for 3/4 of its original size
    pickerFrame.size.width = screenWidth*pickerShrinkFactor;
    pickerFrame.size.height =  pickerHeight*pickerShrinkFactor;
    // You can also set the upper left corner of the picker
    pickerFrame.origin.x = 0;
    // Set the picker frame to new size and origin
           pickerView.frame = pickerFrame;
           // Add it to your view
    [self.view addSubview:pickerView];
   
   }
   

Good luck

回答5:

I'm fairly certain that the UIPicker comes in one size, which you can't change. Would be interested to hear different.

回答6:

The answer is in:

-(UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {

Since with:

- (NSString*)pickerView:(UIPickerView*)pv titleForRow:(NSInteger)row forComponent:(NSInteger)component

Makes it work (that is: sideways with scaled label) of course

回答7:

No problem (I just registered). By the way I just realized that when I posted my answer, that the method (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent .... lost the space between row and forComponent. So make sure that you have the delegate correct or else it will not work.