UIStepper自定义结果为蓝色矩形

Question

我一直在尝试自定义通过Interface Builder添加的 UIStepper 对象的外观。在参考主题here和其他主题时，我为viewDidLoad添加了几行代码。

- (void)viewDidLoad {
    [[UIStepper appearance] setIncrementImage:[UIImage imageNamed:@"stepperupImage.tif"] forState:UIControlStateNormal];
    [[UIStepper appearance] setDecrementImage:[UIImage imageNamed:@"stepperdownImage.tif"] forState:UIControlStateNormal];
}

结果是死亡的蓝色矩形，如下所示。 UIStepper没有像UIButtonTypeCustom这样的UIButton属性。有人知道如何解决这个问题吗？我的部署目标是iOS 8.0。

感谢。

Answer 1

要渲染原本不具有透明度的图像，请执行以下操作：

• 将“渲染为”设置更改为“原始图像”^{（仅限.xcasset文件）}：
  

- 或 -

• 更改代码(docs)中的呈现模式：

  UIImage *image;
  image = [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
  

在您的情况下，代码如下所示：

[[UIStepper appearance] setIncrementImage:[[UIImage imageNamed:@"stepperupImage.tif"] imageWithRenderingMode: UIImageRenderingModeAlwaysOriginal] forState:UIControlStateNormal];
[[UIStepper appearance] setDecrementImage:[[UIImage imageNamed:@"stepperdownImage.tif"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal] forState:UIControlStateNormal];

Answer 2

UIImage *incrementImageFromFile = [UIImage imageNamed:@"plus.png"];
UIImage *incrementImage = [incrementImageFromFile imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

UIImage *decrementImageFromFile = [UIImage imageNamed:@"minus.png"];
UIImage *decrementImage = [decrementImageFromFile imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];



// For Normal state
[stepper setIncrementImage:incrementImage forState:UIControlStateNormal];
[stepper setDecrementImage:decrementImage forState:UIControlStateNormal];

// For Highlighted state
[stepper setIncrementImage:incrementImage forState:UIControlStateHighlighted];
[stepper setDecrementImage:decrementImage forState:UIControlStateHighlighted];