UiPickerView with custom fixed label and autolayout - cocoa

Question

I need to implement a UIPickerView to choose hours, minutes and seconds. I need to have a label, next to each component that stay fixed when the picker spin. For example you can look at the timer section of the Apple Clock app. I put an image for reference
of course I need a picker with 3 components but the problem is the same. I found a lot of solution to add a label as a subview and position it using some frames and manual adjustment but a can' t make it work with AutoLayout and i don' t find a solution on the web. Anyone has solved this problem? thanks

Answer 1

Swift 4.2
After create pickerView add next code:
// Fixed labels
let font = UIFont.systemFont(ofSize: 20.0)
let fontSize: CGFloat = font.pointSize
let componentWidth: CGFloat = self.view.frame.width / CGFloat(agePickerView.numberOfComponents)
let y = (agePickerView.frame.size.height / 2) - (fontSize / 2)
let label1 = UILabel(frame: CGRect(x: componentWidth * 0.65, y: y, width: componentWidth * 0.4, height: fontSize))
label1.font = font
label1.textAlignment = .left
label1.text = "Years"
label1.textColor = UIColor.lightGray
agePickerView.addSubview(label1)
let label2 = UILabel(frame: CGRect(x: componentWidth * 1.65, y: y, width: componentWidth * 0.4, height: fontSize))
label2.font = font
label2.textAlignment = .left
label2.text = "Years"
label2.textColor = UIColor.lightGray
agePickerView.addSubview(label2)
let label3 = UILabel(frame: CGRect(x: componentWidth * 0.05, y: 0, width: componentWidth , height: fontSize))
label3.font = font
label3.textAlignment = .center
label3.text = "From"
label3.textColor = UIColor.lightGray
agePickerView.addSubview(label3)
let label4 = UILabel(frame: CGRect(x: componentWidth * 0.95, y: 0, width: componentWidth , height: fontSize))
label4.font = font
label4.textAlignment = .center
label4.text = "To"
label4.textColor = UIColor.lightGray
agePickerView.addSubview(label4)

Answer 2

I thought others could benefit from my additional answer.
For i components, the following should be in your pickerView initialization method (viewDidLoad),
float fontSize = 20;
float labelWidth = self.view.frame.size.width / [self.myPickerView numberOfComponents];
float y = (self.myPickerView.frame.size.height / 2) - (fontSize / 2);
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(labelWidth* i, y, labelWidth, fontSize)];
label.text = #"Label";
label.font = [UIFont boldSystemFontOfSize:fontSize];
label.backgroundColor = [UIColor clearColor];
label.shadowColor = [UIColor whiteColor];
label.shadowOffset = CGSizeMake (0,1);
label.textAlignment = NSTextAlignmentRight;
[self.myPickerView insertSubview:label aboveSubview:[self.myPickerView.subviews objectAtIndex:[self.myPickerView.subviews count] - 1]];

Answer 3

I faced a similar problem in an App I worked on and decided on the following:
i. Create the UIPicker
ii. Find the midpoint of the presented Picker rows.
iii. Add two UILabels to the screen and in - (void)layoutSubview; make sure the labels are always position next to the midpoints.
I only needed portrait mode support in my project, but should work fine for landscape as well. Just choose a wide enough, row width, such that you do not have any overlap with the data inside the picker. Here a snippet of code for the UIPicker:
#pragma mark - Picker View
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 2;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
if(component == 0) {
return self.hourPickerData.count;
} else {
return self.minutePickerData.count;
}
}
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
return 40;
}
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
return 30;
}
-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
NSString *text;
if(component == 0) {
text = self.hourPickerData[row];
} else {
text = self.minutePickerData[row];
}
UILabel *label = (UILabel*)view;
if(view == nil) {
label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 30)];
label.backgroundColor = [UIColor clearColor];
label.text = text;
label.textAlignment = NSTextAlignmentCenter;
label.textColor = LYTiT_HEADER_COLOR;
label.font = [UIFont fontWithName:LT_HELVETICA size:16];
}
return label;
}