uikit - iOS7 UIPickerView 无法正确显示带有图像的自定义视图

Question

这个问题开始在 iOS7 中使用新的 UIPickerView 控制器发生。要在 UIPickerView 控制器中使用图像，您必须使用委托方法返回图像：

pickerView:viewForRow:forComponent:reusingView:

问题是屏幕随后会出现各种奇怪的行为 - 当您在控件上下移动手指时，图像视图会消失。

Answer 1

这是从 iOS 7.0.2 开始在开发论坛上发布的解决方案：

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    // self.myImages is an array of UIImageView objects
    UIView * myView = [self.myImages objectAtIndex:row];

    // first convert to a UIImage
    UIGraphicsBeginImageContextWithOptions(myView.bounds.size, NO, 0);

    [myView.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage * image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    // then convert back to a UIImageView and return it
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

    return imageView;
}

Answer 2

There is a far simpler way to do it than Ed Trujilo's method (It assumes you are using UIImageView's however ... Ed's method should work for any UIView, I believe).

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    return [[UIImageView alloc] initWithImage: [mpSelections[row] image]];
}