UIPickerView Swift上的奇怪自定义背景颜色

Question

I'm getting strange colors when assigning a custom UIColor to the background of UIPickerViews. I have created a color for textViews and pickerViews as follows:

let myTextViewBackgroundColor = UIColor(red: 192.0/255.0, green: 255.0/255.0, blue: 255.0/255.0, alpha: 0.35)

And I assign it as:

myTextView.backgroundColor = myTextViewBackgroundColor
keywordPicker.backgroundColor = myTextViewBackgroundColor

Here's what it looks like: As you can see, the color of the textViews and the color of the picker are different. The difference seems more pronounced on a device than in this snapshot, but the custom color looks muddy, almost like it is mixed with a default gray background.

If I comment out the pickerView color item above, I get a gray color background: If I choose a standard UIColor, it appears to work correctly. UIColor.yellowColor in this instance. If I choose white, that looks good, too. I create the pickerView in code and assign it to a textField which has no background color assigned.

var keywordPicker : UIPickerView?

keywordPicker = UIPickerView()
keywordPicker?.delegate = self
keywordPicker?.dataSource = self

keywordsForItemTextField.inputView = keywordPicker
keywordPicker.backgroundColor = myTextViewBackgroundColor

And for what it's worth, I have a date picker that I created as a modal screen with it's own view controller. In that case, the picker is created on the storyboard. I still assign my background color with code and that picker shows the correct color.

Answer 1

tkanzakic's answer finally allowed me to change the background color of UIDatePicker.

Here's the Swift 4 version:

class CustomDatePicker: UIDatePicker {

    var customBackgroundColor = UIColor.black

    override func willMove(toWindow newWindow: UIWindow?) {
        super.willMove(toWindow: newWindow)

        if newWindow != nil {
            inputView?.backgroundColor = customBackgroundColor
        }
    }
}

Change the customBackgroundColor property to your liking.

Answer 2

我很确定这是UIPickerView总是在它上面有银灰色滤镜的结果（当你把它设置为白色时注意它是灰色的吗？）

Answer 3

This response does not expose the cause of the issue, but I've included my resolution in case it will help others. I created a label for the selected row display and set the background color of the label. This label color is true to the custom settings.

I give a nod to Making App Pie and article https://makeapppie.com/2014/10/21/swift-swift-formatting-a-uipickerview/ which was the inspiration. Set the background to white:

    keywordPicker?.backgroundColor = UIColor.whiteColor()

Also I added a border so the picker looks like the textViews I created:

    keywordPicker?.layer.borderColor = UIColor(colorLiteralRed: 212.0/255.0, green: 212.0/255.0, blue: 212.0/255.0, alpha: 1.0).CGColor
    keywordPicker?.layer.borderWidth = 1.0
    keywordPicker?.layer.cornerRadius = 7.0
    keywordPicker?.layer.masksToBounds = true

Setup the label:

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

    let pickerLabel = UILabel()
    var titleData : String = String()

    if pickerView == keywordPicker {
        titleData = crsuKeywordPickerList![row]
    }
    pickerLabel.text = titleData

    pickerLabel.backgroundColor = myPickerBackgroundColor
    pickerLabel.textAlignment = .Center

    return pickerLabel

}//pickerView:viewForRow:...

The result:

As a second option as discussed above, if you instantiate the picker on the storyboard this problem does not appear.

Answer 4

In our case we have a wrapper around the UIPickerView to build a custom date picker. After setting the appearance proxy of the UITextField class to use dark mode for the inputView we have the same glitch if the first textField that becomes active is one with the custom picker as inputView , but if the user interact before with a textField with the normal keyboard as inputView the glitch do not appear.

In our particular case adding this hack to the wrapper view fix the issue:

- (void)willMoveToWindow:(UIWindow *)newWindow
{
    [super willMoveToWindow:newWindow];

    if (newWindow) {
        self.pickerView.backgroundColor = self.colorPalette.inputViewBackgroundColor;
    }
}

We also tried setting the color in the willMoveToSuperview: method but that does not work.

Answer 5

write your background color change code inside:-

func textFieldDidBeginEditing(_ textField: UITextField) { 

    if textField == self.tourtextfieldtextField {
        //for background color of picker
        datePickerView.backgroundColor = .red
        //text color of picker
        datePickerView.setValue( colorLiteral(red: 0, green: 0.5529411765, blue: 0.537254902, alpha: 1), forKeyPath: "textColor")
        datePickerView.setValue(0.8, forKeyPath: "alpha")
    }
}

Answer 6

swift 4.2 / xcode 10:

The background color need to be set in the main thread:

DispatchQueue.main.async {
keywordPicker.backgroundColor = myTextViewBackgroundColor
}