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Friday, August 20, 2010

Create UIPickerView programmatically

The UIPickerView is one of the input controls in iOS for displaying and selecting a list of data. Most tutorials implement this control in Interface Builder, which is fine, but I like to have more control and do most everything in code. There are several components to doing this 100% programmatically, which I will demonstrate below...

The first thing we have to do is include the UIPickerViewDelegate in the interface of our class .h file.
@interface myViewController : UIViewController<UIPickerViewDelegate>

Next, actually create the UIPickerView by setting the frame, setting the delegate, making the selection highlight visible and adding it to the main view.
UIPickerView *myPickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 200, 320, 200)];
myPickerView.delegate = self;
myPickerView.showsSelectionIndicator = YES;
[self.view addSubview:myPickerView];

Finally, we have to implement the delegate methods to control the look and functionality.
- (void)pickerView:(UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent:(NSInteger)component {
    // Handle the selection
}

// tell the picker how many rows are available for a given component
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    NSUInteger numRows = 5;

    return numRows;
}

// tell the picker how many components it will have
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
 return 1;
}

// tell the picker the title for a given component
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    NSString *title;
    title = [@"" stringByAppendingFormat:@"%d",row];

    return title;
}

// tell the picker the width of each row for a given component
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
 int sectionWidth = 300;

 return sectionWidth;
}

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