cocoa-touch - UIButton : Add gradient layer and title is not shown anymore - how to fix?

Question

我正在使用下面的代码向 UIButton 添加渐变层。工作正常，但标题不再可见。有人知道如何修复吗？

UIButton oAddressBtn = UIButton.FromType (UIButtonType.Custom);
oAddressBtn.Frame = new RectangleF (0, 0, 150, 25);
oAddressBtn.VerticalAlignment = UIControlContentVerticalAlignment.Center;
oAddressBtn.Font = UIFont.FromName("Helvetica", 12);
oAddressBtn.SetTitleColor (UIColor.White, UIControlState.Normal);

// Create a gradient for the background.
CAGradientLayer oGradient = new CAGradientLayer ();
oGradient.Frame = oAddressBtn.Bounds;
oGradient.Colors = new CGColor[] { UIColor.FromRGB (170, 190, 235).CGColor, UIColor.FromRGB (120, 130, 215).CGColor };

// Assign gradient to the button.
oAddressBtn.Layer.MasksToBounds = true;
oAddressBtn.Layer.AddSublayer (oGradient);
oAddressBtn.Layer.CornerRadius = 10;
oAddressBtn.Layer.BorderColor = UIColor.FromRGB (120, 130, 215).CGColor;

// Set the button's title.
oAddressBtn.SetTitle (sAddress, UIControlState.Normal);

Answer 1

哈!问一个问题，然后自己找出来……巧合。
我不得不改变顺序。分配渐变后，必须设置按钮的文本属性而不是之前。固定代码在这里:

UIButton oAddressBtn = UIButton.FromType (UIButtonType.Custom);
oAddressBtn.Frame = new RectangleF (0, 0, 150, 25);

// Create a gradient for the background.
CAGradientLayer oGradient = new CAGradientLayer ();
oGradient.Frame = oAddressBtn.Bounds;
oGradient.Colors = new CGColor[] { UIColor.FromRGB (170, 190, 235).CGColor, UIColor.FromRGB (120, 130, 215).CGColor };

// Assign gradient to the button.
oAddressBtn.Layer.MasksToBounds = true;
oAddressBtn.Layer.AddSublayer (oGradient);
oAddressBtn.Layer.CornerRadius = 10;
oAddressBtn.Layer.BorderColor = UIColor.FromRGB (120, 130, 215).CGColor;

// Set the button's title. Alignment and font have to be set here to make it work.
oAddressBtn.VerticalAlignment = UIControlContentVerticalAlignment.Center;
oAddressBtn.Font = UIFont.FromName("Helvetica", 12);
oAddressBtn.SetTitleColor (UIColor.White, UIControlState.Normal);

oAddressBtn.SetTitle (sAddress, UIControlState.Normal);