更改UISlider thumbImage的大小 [英] Change the size of a UISlider thumbImage

问题描述

如何更改我用作thumbImage的UIImage的大小。我用来设置图像的代码如下。

How can I change the size of a UIImage that I am using as a thumbImage. The code I use to set the image is as follows.

let image: UIImage = UIImage(assetIdentifier: UIImage.AssetIdentifier.Slider)

我使用Enum来获取图像，没问题。

I use an Enum to get the image, no problem there.

我用来设置thumbImage的代码如下。

The code I use to set the thumbImage is as follows.

self.setThumbImage(image, forState: UIControlState.Normal)

我尝试使用下面的代码更改拇指图像大小但不能找到解决方案。

I have tried using the code below to change the thumb images size but cannot find the solution.

let trackRect: CGRect = CGRect(x: 0.0, y: 0, width: self.frame.size.width, height: self.frame.size.height)
let thumbRect: CGRect = CGRect(x: 0.0, y: 0.0, width: 12.0, height: 12.0)
thumbRectForBounds(thumbRect, trackRect: trackRect, value: 0.0)

图像目前大约是40pt到40pt（它是一个圆圈）。我希望图像大约在24pt到24pt左右。

The image is currently about 40pt by 40pt (Its a circle). I would like the image to be around 24pt by 24pt.

此外，这是在XCode 7上的Swift 2.我理解这些方法适用于iOS8.0或更高版本这是我的部署目标。

Also, this is in Swift 2 on XCode 7. I understand those methods are for iOS8.0 or above and that is my deployment target.

推荐答案

拇指将是您提供的图像的大小。
要获得一个24pt乘24pt的拇指，你必须提供48px乘48px（和72x72 @ 3）图像。这也会影响滑块框架。

The thumb will be the size of the image you provide. To get a 24pt by 24pt thumb, you must provide 48px by 48px (and 72x72 for @3) image. This also affects the slider frame.

如果需要，您可以定义一个扩展来动态调整图像大小：

You can define an extension to resize images on the fly if needed:

extension UIImage
{
    func imageWithImage(image: UIImage, scaledToSize newSize: CGSize) -> UIImage
    {    
         UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)
         image.drawInRect(CGRectMake(0, 0, newSize.width, newSize.height))

         let newImage = UIGraphicsGetImageFromCurrentImageContext()    
         UIGraphicsEndImageContext()

         return newImage;
    }
}

这样你甚至可以做一些像拇指增大和缩小的滑块，因为它接近最大值和最小值。

That way you can even do cool stuff like have a slider where the thumb grows and shrinks, as it approaches max and min values.

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