Spacing Issue with SwiftUI - swiftui

Question

I am experiencing a weird spacing behavior that I'm hoping someone can explain. I have two views, the main view (ContentView) contains a child view called PlayerToolbar. The desired behavior is for ContentView take up the entire screen with PlayerToolbar being rendered at the very bottom of the screen. PlayerToolbar contains image buttons and spacers. The issue I am running into is ContentView only takes up a portion of the screen and PlayerToolbar is not aligned to the bottom as shown in the image.
Here is the code for ContentView
struct ContentView: View {
var body: some View {
VStack{
Spacer()
Text("Main Content")
Spacer()
PlayerToolBar()
}.background(Color.blue)
}
}
And here is the code for PlayerToolbar:
struct PlayerToolBar: View {
var body: some View {
HStack{
Spacer()
Button(action: {
print("backward button pressed")
}){
Image(systemName: "gobackward.10").renderingMode(.original) .resizable().aspectRatio(contentMode: .fit)
}
Spacer()
Button(action: {
print("play button pressed")
}){
Image(systemName: "play.circle").renderingMode(.original) .resizable().aspectRatio(contentMode: .fit)
}
Spacer()
Button(action: {
print("go forward button pressed")
}){
Image(systemName: "goforward.10").renderingMode(.original) .resizable().aspectRatio(contentMode: .fit)
}
Spacer()
Button(action: {
print("jot button pressed")
}){
Image(systemName: "pencil.circle").renderingMode(.original) .resizable().aspectRatio(contentMode: .fit)
}
Spacer()
}.background(Color(UIColor.secondarySystemBackground))
}
}
I have found that if add one Text object in my PlayerToolbar between the first Spacer and Button, the screen renders as I expect
...
Spacer()
Text(" ")
Button(action: {
print("backward button pressed")
}){
Image(systemName: "gobackward.10").renderingMode(.original) .resizable().aspectRatio(contentMode: .fit)
}
...
Any idea of why it is behaving the way it is and why a Text makes it act the way I prefer?

Answer 1

The problem, I think, is because your PlayerToolbar has no height and it is hard for the layout logic to determine one. Nothing in your PlayerToolbar has an explicit height. Your images are made resizable, but nothing in your views is telling how to resize them.
By adding a Text() view, your images now have some height to match, and so it works as you expect it.
Other solutions to break the ambiguity are (choose any, not all):
Set a frame height to the PlayerToolbar:
PlayerToolBar().frame(height: 40)
Set the height for at least one of your images:
Image(systemName: "gobackward.10")
.renderingMode(.original)
.resizable()
.frame(height: 40)
.aspectRatio(contentMode: .fit)
Set the height to one of your buttons:
Button(action: {
print("backward button pressed")
}){
Image(systemName: "gobackward.10")
.renderingMode(.original)
.resizable()
.aspectRatio(contentMode: .fit)
}.frame(height: 40)
Set the height of the HStack in your PlayerToolbar.
Remove the resizable() modifier in at least one of your images.
Image(systemName: "pencil.circle").renderingMode(.original).aspectRatio(contentMode: .fit)
All these alternatives aim at the same thing, making sure your images know how much to grow/shrink. There are of course many other options. These are just a few.