DAY 23 (Project 3, part 1)

Custom containers

SwiftUIは自動的にセルクロージャー内に暗黙の水平スタックを作成します。

import SwiftUI

struct ContentView: View {
    var body: some View {
        GridStack(rows: 4, columns: 4) { row, col in
            Text("R\(row) C\(col)")
        }
    }
}
struct GridStack<Content: View>: View {
    let rows: Int
    let columns: Int
    let content: (Int, Int) -> Content

    var body: some View {
        VStack {
            ForEach(0..<rows, id: \.self) { row in
                HStack {
                    ForEach(0..<self.columns, id: \.self) { column in
                        self.content(row, column)
                    }
                }
            }
        }
    }
}

import SwiftUI
struct ContentView: View {
    var body: some View {
        GridStack(rows: 4, columns: 4) { row, col in
            Image(systemName: "\(row * 4 + col).circle")
            Text("R\(row) C\(col)")
        }
    }
}

struct GridStack<Content: View>: View {
    let rows: Int
    let columns: Int
    let content: (Int, Int) -> Content
    
    init(rows: Int, columns: Int, @ViewBuilder content: @escaping (Int, Int) -> Content) {
        self.rows = rows
        self.columns = columns
        self.content = content
    }

    var body: some View {
        VStack {
            ForEach(0..<rows, id: \.self) { row in
                HStack {
                    ForEach(0..<self.columns, id: \.self) { column in
                        self.content(row, column)
                    }
                }
            }
        }
    }
}

SwiftUIビューの背後

struct ContentView: View {
    var body: some View {
        Text("Hello World")
            .background(Color.red)
    }
}


Text("Hello World")
    .frame(maxWidth: .infinity, maxHeight: .infinity)
    .background(Color.red)


Text("Hello World")
    .frame(maxWidth: .infinity, maxHeight: .infinity)
    .background(Color.red)
    .edgesIgnoringSafeArea(.all)

修飾子の順序

Button("Hello World") {
    // do nothing
}    
.background(Color.red)
.frame(width: 200, height: 200)

Button("Hello World") {
    print(type(of: self.body))
}    
.background(Color.red)
.frame(width: 200, height: 200)


Button("Hello World") {
    print(type(of: self.body))
}
.frame(width: 200, height: 200)
.background(Color.red)


Text("Hello World")
    .padding()
    .background(Color.red)
    .padding()
    .background(Color.blue)
    .padding()
    .background(Color.green)
    .padding()
    .background(Color.yellow)

条件付き修飾子

struct ContentView: View {
    @State private var useRedText = false

    var body: some View {
        Button("Hello World") {
            // flip the Boolean between true and false
            self.useRedText.toggle()            
        }
        .foregroundColor(useRedText ? .red : .blue)
    }
}

プロパティとしてのビュー

struct ContentView: View {
    let motto1 = Text("Draco dormiens")
    let motto2 = Text("nunquam titillandus")

    var body: some View {
        VStack {
            motto1
            motto2
        }
    }
}


VStack {
    motto1
        .foregroundColor(.red)
    motto2
        .foregroundColor(.blue)
}


var motto1: some View { Text("Draco dormiens") }

構成を表示

struct ContentView: View {
    var body: some View {
        VStack(spacing: 10) {
            Text("First")
                .font(.largeTitle)
                .padding()
                .foregroundColor(.white)
                .background(Color.blue)
                .clipShape(Capsule())

            Text("Second")
                .font(.largeTitle)
                .padding()
                .foregroundColor(.white)
                .background(Color.blue)
                .clipShape(Capsule())
        }
    }
}


struct CapsuleText: View {
    var text: String

    var body: some View {
        Text(text)
            .font(.largeTitle)
            .padding()
            .foregroundColor(.white)
            .background(Color.blue)
            .clipShape(Capsule())
    }
}


VStack(spacing: 10) {
    CapsuleText(text: "First")
        .foregroundColor(.white)
    CapsuleText(text: "Second")
        .foregroundColor(.yellow)
}

カスタム修飾子

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack(spacing:20){
        Text("Hello World")
            .modifier(Title())
        
        Text("Hello World")
            .titleStyle()
        }
    }
}

struct Title: ViewModifier {
    func body(content: Content) -> some View {
        content
            .font(.largeTitle)
            .foregroundColor(.white)
            .padding()
            .background(Color.blue)
            .clipShape(RoundedRectangle(cornerRadius: 10))
    }
}

extension View {
    func titleStyle() -> some View {
        self.modifier(Title())
    }
}

import SwiftUI

struct ContentView: View {
    var body: some View {
       Color.blue
        .frame(width: 300, height: 200)
        .watermarked(with: "Hacking with Swift")
    }
}

struct Watermark: ViewModifier {
    var text: String

    func body(content: Content) -> some View {
        ZStack(alignment: .bottomTrailing) {
            content
            Text(text)
                .font(.caption)
                .foregroundColor(.white)
                .padding(5)
                .background(Color.black)
        }
    }
}

extension View {
    func watermarked(with text: String) -> some View {
        self.modifier(Watermark(text: text))
    }
}