SwiftUI text-alignment

You can do this via the modifier .multilineTextAlignment(.center).

Text("CENTER")
    .multilineTextAlignment(.center)

Apple Documentation

From SwiftUI beta 3 forward, you can center a text view with the frame modifier:

Text("Centered")
    .frame(maxWidth: .infinity, alignment: .center)

Was trying to understand this myself as other answers here mention Text.multilineTextAlignment(_:) / VStack(alignment:) / frame(width:alignment:) but each solution solves a specific problem. Eventually it depends on the UI requirement and a combination of these.

---

VStack(alignment:)

The alignment here is for the inner views in respective to one another.
So specifying .leading would associate all inner views to have their leading aligned with one another.

VStack(alignment: .leading, spacing: 6) {
  Text("Lorem ipsum dolor")
        .background(Color.gray.opacity(0.2))
  Text("sit amet")
        .background(Color.gray.opacity(0.2))
}
.background(Color.gray.opacity(0.1))

---

.frame

In frame(width:alignment:) or frame(maxWidth:alignment:), the alignment is for the contents within the given width.

VStack(alignment: .leading, spacing: 6) {
  Text("Lorem ipsum dolor")
      .background(Color.gray.opacity(0.2))
  Text("sit amet")
      .background(Color.gray.opacity(0.2))
}
.frame(width: 380, alignment: .trailing)
.background(Color.gray.opacity(0.1))

The inners views are leading aligned respective to one another but the views themselves are trailing aligned respective to the VStack.

---

.multilineTextAlignment

This specifies the alignment of the text inside and can be seen best when there are multiple lines otherwise without a defined frame(width:alignment), the width is automatically adjusted and gets affected by the default alignments.

VStack(alignment: .trailing, spacing: 6) {
  Text("0. automatic frame\n+ view at parent's specified alignment\n+ multilineTA not set by default at leading")
    .background(Color.gray.opacity(0.2))
  Text("1. automatic frame\n+ view at parent's specified alignment\n+ multilineTA set to center")
  .multilineTextAlignment(.center)
  .background(Color.gray.opacity(0.2))
  Text("2. automatic frame\n+ view at parent's specified alignment\n+ multilineTA set to trailing")
  .multilineTextAlignment(.trailing)
  .background(Color.gray.opacity(0.2))
}
.frame(width: 380, alignment: .trailing)
.background(Color.gray.opacity(0.1))

---

Tests with combinations:

VStack(alignment: .trailing, spacing: 6) {
  Text("1. automatic frame, at parent's alignment")
  .background(Color.gray.opacity(0.2))
  Text("2. given full width & leading alignment\n+ multilineTA at default leading")
  .frame(maxWidth: .infinity, alignment: .leading)
  .background(Color.gray.opacity(0.2))
  Text("3. given full width & center alignment\n+ multilineTA at default leading")
  .frame(maxWidth: .infinity, alignment: .center)
  .background(Color.gray.opacity(0.2))
  Text("4. given full width & center alignment\n+ multilineTA set to center")
  .multilineTextAlignment(.center)
  .frame(maxWidth: .infinity, alignment: .center)
  .background(Color.gray.opacity(0.2))
  Text("5. given full width & center alignment\n+ multilineTA set to trailing")
  .multilineTextAlignment(.trailing)
  .frame(maxWidth: .infinity, alignment: .center)
  .background(Color.gray.opacity(0.2))
  Text("6. given full width but no alignment\n+ multilineTA at default leading\n+ leading is based on content, looks odd sometimes as seen here")
  .frame(maxWidth: .infinity)
  .background(Color.gray.opacity(0.2))
}
.frame(width: 380)
.background(Color.gray.opacity(0.1))