点击选定的UIButton时，UIButton突出显示的状态不显示

Question

当我点击已经选中的按钮时，我希望我的UIButton显示突出显示的状态。

基本上在突出显示的状态下，我将* .png图像应用为我的UIButton背景图像，以提供按下的效果。

但是如果按钮已经处于选中状态当我再次点击它时，我看不到突出显示的状态，但它直接进入正常状态！

观看问题 - > Video of the Issue!

请帮忙

//0    init UIButton
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(x, y, aSide, aSide)];

//1    Give it a backgroundColor
[button setBackgroundColor:aColor];

[..]

//2    Set titleLabel and its style
[button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[button setTitleColor:[UIColor redColor] forState:UIControlStateSelected];
[button setTitleColor:[UIColor grayColor] forState:UIControlStateHighlighted];

UIImage *shadowImage = [UIImage imageNamed:kBtnShadow];
shadowImage = [shadowImage stretchableImageWithLeftCapWidth:floorf(shadowImage.size.width/2) topCapHeight:floorf(shadowImage.size.height/2)];

[button setBackgroundImage:shadowImage forState: UIControlStateHighlighted];

[button setTitle:aLabel forState:  UIControlStateNormal];

//3    Assign tag and Action
[button setTag:tag];
[button addTarget:target action:a forControlEvents:UIControlEventTouchUpInside];

Answer 1

各种状态：UIControlStateNormal，UIControlStateSelected和(UIControlStateSelected | UIControlStateHighlighted)都是截然不同的。如果您希望shadowImage同时应用于（仅）突出显示状态和突出显示的+选定状态，则还必须设置：

[button setBackgroundImage:shadowImage forState:(UIControlStateHighlighted | UIControlStateSelected)]

Answer 2

在swift，这将是：

button.setBackgroundImage(shadowImage, forState: UIControlState.Selected.union(UIControlState.Highlighted))

Answer 3

在Swift v3（2016年11月）中：

button.setBackgroundImage(shadowImage, for: UIControlState.selected.union(UIControlState.highlighted))

Answer 4

Swift 4.2

仅适用于编程方式。

aButton.setImage(UIImage(named: "your_image"), for: [.selected, .highlighted])