changing font and its size of a picker in swift

Question

With Objective-C, I used the code shown below to set/change font family and size of a picker:

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
UILabel* tView = (UILabel*)view;
if (!tView){
    tView = [[UILabel alloc] init];
    // Setup label properties - frame, font, colors etc
    tView.font = [UIFont fontWithName:@"Times New Roman" size:fontsize];;
}
tView.text = [_mysitedata findKeyForRow:row];
NSLog(@"C key:%@ row:%ld comp:%ld", tView.text, (long int)row, (long int)component);
return tView;
}

However, Swift does not accept a cast from UIView to UILabel and hence I can not follow this path which would look something like shown below:

func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView?) -> UIView {
    let label = view as! UILabel
    label.font = UIFont(name: "Times New Roman", size: 1.0)
    label.text = pickerData[row]
    return label
}

The first stament (let label ....) throuws an exception at run time:

EXC-BAD INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

Answer 1

A more idiomatic Swift coding would be:

func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView?) -> UIView {
  guard let label = view as? UILabel else {
    preconditionFailure ("Expected a Label")
  }

  label.font = UIFont(name: "Times New Roman", size: 1.0)
  label.text = pickerData[row]
  return label
}