diff --git a/Tetris/ContentView.swift b/Tetris/ContentView.swift
index defbd56..8ab759a 100644
--- a/Tetris/ContentView.swift
+++ b/Tetris/ContentView.swift
@@ -22,8 +22,20 @@ struct ContentView: View {
     var body: some View {
         GeometryReader { (geometry) in
             VStack {
+                HStack {
+                    VStack(spacing: 0) {
+                        Text("Held")
+                        if self.controller.heldTetromino != nil {
+                            Group {
+                                TetrominoView(tetromino: self.controller.heldTetromino!)
+                            }.frame(width: 50, height: 50, alignment: .center)
+                        } else {
+                            Rectangle().foregroundColor(.clear).frame(width: 50, height: 50)
+                        }
+                    }
+                }
                 BoardView(board: self.$controller.board, currentPiece: self.$controller.currentPiece, droppedPiece: self.$controller.currentPieceAtDropPoint)
-                    .aspectRatio(CGSize(width: 10, height: 16), contentMode: .fit)
+                    .aspectRatio(CGSize(width: self.controller.width, height: self.controller.height), contentMode: .fit)
                     .onAppear(perform: self.startTimer)
                     .onDisappear(perform: self.stopTimer)
                     .onTapGesture(perform: self.onTap)
@@ -32,9 +44,15 @@ struct ContentView: View {
                 //            .gesture(horizDragGesture.simultaneously(with: verticalDragGesture))
 
                 HStack {
+                    Spacer()
+                    Button(action: self.controller.hold) {
+                        Image(systemName: "arrow.up.square.fill").resizable().frame(width: 50, height: 50)
+                    }
+                    Spacer()
                     Button(action: self.onTap) {
                         Image(systemName: "goforward").resizable().frame(width: 50, height: 50)
                     }
+                    Spacer()
                 }
                 HStack {
                     Button(action: self.controller.left) {
@@ -107,7 +125,7 @@ struct ContentView: View {
     }
     
     func onSwipeUp() {
-        // hold
+        self.controller.hold()
     }
     
     func onSwipeDown() {
diff --git a/TetrisKit/GameController.swift b/TetrisKit/GameController.swift
index 21291c6..9e25f47 100644
--- a/TetrisKit/GameController.swift
+++ b/TetrisKit/GameController.swift
@@ -24,6 +24,7 @@ public class GameController: ObservableObject {
         }
     }
     @Published public var currentPieceAtDropPoint: GamePiece?
+    @Published public var heldTetromino: Tetromino?
 
     public var ended: Bool {
         return (0..<width).first(where: { board[$0, 0] }) != nil
@@ -40,8 +41,8 @@ public class GameController: ObservableObject {
     }
     
     func nextPiece() {
-        currentPiece = GamePiece(tetromino: .random())
-        currentPiece!.topLeft = ((width - currentPiece!.tiles.count) / 2, 0)
+        let tetromino = Tetromino.random()
+        currentPiece = GamePiece(tetromino: tetromino, topLeft: ((width - tetromino.shape.count) / 2, 0))
     }
     
     func finalizePiece() {
@@ -49,9 +50,7 @@ public class GameController: ObservableObject {
         clearLines()
         nextPiece()
         
-        if case .playing(.dropped) = state {
-            state = .playing(.normal)
-        }
+        state = .playing(.normal)
     }
     
     func clearLines() {
@@ -80,7 +79,8 @@ public class GameController: ObservableObject {
     }
     
     public func rotate(direction: RotationDirection) {
-        guard case .playing(_) = state,
+        guard case let .playing(playState) = state,
+            playState != .dropped,
             let currentPiece = currentPiece else { return }
         
         let modifiedPiece = currentPiece.rotated(direction)
@@ -90,7 +90,8 @@ public class GameController: ObservableObject {
     }
     
     public func left() {
-        guard case .playing(.normal) = state,
+        guard case let .playing(playState) = state,
+            playState != .dropped,
             let currentPiece = currentPiece else { return }
         let modifiedPiece = currentPiece.moved(by: (-1, 0))
         if !overlapsAny(modifiedPiece) {
@@ -99,7 +100,8 @@ public class GameController: ObservableObject {
     }
     
     public func right() {
-        guard case .playing(.normal) = state,
+        guard case let .playing(playState) = state,
+            playState != .dropped,
             let currentPiece = currentPiece else { return }
         let modifiedPiece = currentPiece.moved(by: (1, 0))
         if !overlapsAny(modifiedPiece) {
@@ -108,11 +110,24 @@ public class GameController: ObservableObject {
     }
     
     public func drop() {
-        guard case .playing(.normal) = state else { return }
+        guard case let .playing(playState) = state, playState != .dropped else { return }
         currentPiece = currentPieceAtDropPoint
         state = .playing(.dropped)
     }
     
+    public func hold() {
+        guard case .playing(.normal) = state,
+            let currentPiece = currentPiece else { return }
+        if let heldTetromino = heldTetromino {
+            self.heldTetromino = currentPiece.tetromino
+            self.currentPiece = GamePiece(tetromino: heldTetromino, topLeft: ((width - heldTetromino.shape.count) / 2, 0))
+        } else {
+            heldTetromino = currentPiece.tetromino
+            nextPiece()
+        }
+        state = .playing(.switched)
+    }
+    
     private func updateCurrentPieceAtDropPoint() {
         guard let currentPiece = currentPiece else { return }
         var prev = currentPiece
@@ -146,4 +161,5 @@ enum GameState {
 enum PlayState {
     case normal
     case dropped
+    case switched
 }
diff --git a/TetrisKit/GamePiece.swift b/TetrisKit/GamePiece.swift
index 8484dbf..05c4833 100644
--- a/TetrisKit/GamePiece.swift
+++ b/TetrisKit/GamePiece.swift
@@ -13,10 +13,10 @@ public struct GamePiece {
     public var topLeft: (Int, Int)
     public internal(set) var tiles: [[Bool]]
     
-    public init(tetromino: Tetromino) {
+    public init(tetromino: Tetromino, topLeft: (Int, Int) = (0, 0)) {
         self.tetromino = tetromino
         self.tiles = tetromino.shape
-        self.topLeft = (0, 0)
+        self.topLeft = topLeft
     }
     
     mutating func rotate(direction: RotationDirection) {
diff --git a/TetrisUI/GridView.swift b/TetrisUI/GridView.swift
index 8642c64..83aac3c 100644
--- a/TetrisUI/GridView.swift
+++ b/TetrisUI/GridView.swift
@@ -23,9 +23,9 @@ struct GridView<Cell>: View where Cell: View {
     var body: some View {
         GeometryReader { (geometry) in
             VStack(spacing: 0) {
-                ForEach(0..<self.rows) { (row) in
+                ForEach(0..<self.rows, id: \.self) { (row) in
                     HStack(spacing: 0) {
-                        ForEach(0..<self.columns) { (col) in
+                        ForEach(0..<self.columns, id: \.self) { (col) in
                             self.cellProvider(col, row, self.cellSize(for: geometry))
                         }
                     }
diff --git a/TetrisUI/TetrominoView.swift b/TetrisUI/TetrominoView.swift
new file mode 100644
index 0000000..d63add2
--- /dev/null
+++ b/TetrisUI/TetrominoView.swift
@@ -0,0 +1,61 @@
+//
+//  TetrominoView.swift
+//  Tetris
+//
+//  Created by Shadowfacts on 10/15/19.
+//  Copyright © 2019 Shadowfacts. All rights reserved.
+//
+
+import SwiftUI
+import TetrisKit
+
+public struct TetrominoView: View {
+    let tetromino: Tetromino
+    
+    public init(tetromino: Tetromino) {
+        self.tetromino = tetromino
+    }
+    
+    public var body: some View {
+        GridView(rows: self.rows, columns: self.columns) { (col, row, size) in
+            Rectangle()
+                .foregroundColor(self.colorAt(col, row))
+                .frame(width: size, height: size)
+        }
+    }
+    
+    var rows: Int {
+        self.tetromino.shape.firstIndex(where: { row in
+            row.allSatisfy({ el in
+                !el
+            })
+        }) ?? self.tetromino.shape.count
+    }
+    
+    var columns: Int {
+        self.tetromino.shape.map { row in
+            (row.firstIndex(where: { el in
+                !el
+            }) ?? row.count - 1) + 1
+        }.max() ?? self.tetromino.shape.first!.count
+    }
+    
+    func colorAt(_ col: Int, _ row: Int) -> Color {
+        if row < tetromino.shape.count && col < tetromino.shape[row].count && tetromino.shape[row][col] {
+            return tetromino.color
+        } else {
+            return .clear
+        }
+    }
+}
+
+struct TetrominoView_Previews: PreviewProvider {
+    static var previews: some View {
+        Group {
+            TetrominoView(tetromino: .t)
+            TetrominoView(tetromino: .i)
+            TetrominoView(tetromino: .z)
+            TetrominoView(tetromino: .j)
+        }
+    }
+}