小编sub*_*dan的帖子

如何在Swift中将Int转换为UInt8？例.我想将22号转换为0b00010110

var decimal = 22
var binary:UInt8 = ??? //What should I write here?

I have a large image in Assets.xcassets. How to resize this image with SwiftUI to make it small?

I tried to set frame but it doesn't work:

Image(room.thumbnailImage)
    .frame(width: 32.0, height: 32.0)

I have a Button. I want to set custom background color for highlighted state. How can I do it in SwiftUI?

Button(action: signIn) {
    Text("Sign In")
}
.padding(.all)
.background(Color.red)
.cornerRadius(16)
.foregroundColor(.white)
.font(Font.body.bold())

我有字符串变量:var str ="239A23F"如何将此字符串转换为二进制数？ str.toInt()不起作用.

我想用if-let语句解包可选值.我需要获得MKAnnotation的标题.

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    if let title = view.annotation?.title {
        print(title) //Optional("Moscow")
    }
}

为什么if-let在这里不起作用？