在swift中更改字体及其选择器的大小

Question

使用Objective-C,我使用下面显示的代码来设置/更改选择器的字体系列和大小:

- (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;
}

但是,Swift不接受从UIView到UILabel的演员阵容,因此我不能遵循这条看起来如下所示的路径:

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
}

第一个版本(让标签....)在运行时引发异常:

EXC-BAD INSTRUCTION(代码= EXC_I386_INVOP,子代码= 0x0)

Answer 1

对于Swift 3

 func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
    let label = (view as? UILabel) ?? UILabel()

    label.textColor = .black
    label.textAlignment = .center
    label.font = UIFont(name: "SanFranciscoText-Light", size: 18)

    // where data is an Array of String
    label.text = pickerData[row]

    return label
  }

Answer 2

要更改字体名称和大小,您可以使用viewForRow和属性字符串:

func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView?) -> UIView {

    var label = view as! UILabel!
    if label == nil {
        label = UILabel()
    }

    var data = pickerData[row]
    let title = NSAttributedString(string: data!, attributes: [NSFontAttributeName: UIFont.systemFontOfSize(36.0, weight: UIFontWeightRegular)])
    label.attributedText = title
    label.textAlignment = .Center
    return label

}

如果你使字体大小变大,你会想用rowHeightForComponent增加每行的高度:

func pickerView(pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
    return 36.0
}

Answer 3

如果要将选取器标签贴到AUTOSHRINK ...

设置adjustsFontSizeToFitWidth=true和minimumScaleFactor=0.5

func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {

    var label: UILabel
    if let view = view as? UILabel { label = view }
    else { label = UILabel() }

    label.text = "..."
    label.textAlignment = .center
    label.font = UIFont.boldSystemFont(ofSize: 20)
    label.adjustsFontSizeToFitWidth = true
    label.minimumScaleFactor = 0.5

    return label
}

Answer 4

更惯用的 Swift 编码是：

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
}