在swift中更改选择器的字体及其大小

对于Objective-C，我使用以下代码设置/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的转换，因此我无法遵循如下所示的路径：

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
}

第一个语句（let label…）在运行时通过异常：

EXC-BAD指令（代码=EXC\U I386\U INVOP，子代码=0x0）

---

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
}

---

要更改字体名称和大小，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

}

如果将字体大小增大，则需要使用rowHeightForComponent增加每行的高度：

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

斯威夫特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
  }

---

适用于swift 2.3

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

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

        label.font = UIFont(name: "Lato-Regular", size: 17)!
        label.text =  dataArray[row] as? String
        label.textAlignment = .Center
        return label

    }

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

        print("Returning Custom label")
        var label = view as! UILabel!
        if label == nil {
            label = UILabel()
        }

        label?.font = UIFont(name: "Lato-Regular", size: 14)!
        label?.text =  dataArray[row] as? String
        label?.textAlignment = .center
        return label!

    }

适用于Swift 3

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

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

        label.font = UIFont(name: "Lato-Regular", size: 17)!
        label.text =  dataArray[row] as? String
        label.textAlignment = .Center
        return label

    }

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

        print("Returning Custom label")
        var label = view as! UILabel!
        if label == nil {
            label = UILabel()
        }

        label?.font = UIFont(name: "Lato-Regular", size: 14)!
        label?.text =  dataArray[row] as? String
        label?.textAlignment = .center
        return label!

    }

---

如果希望选择器标签自动收缩…

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
}

---

此链接[链接]解决了问题。您还可以将前几行替换为：let label=（查看为？UILabel）？？UILabel（）对于像我这样在尝试这种方法时出错并花费太多时间试图找出错误的人，另一种可行的方法是：