I have an issue with SwiftUI not accepting the > condition.
Not sure if I am doing someone wrong..
It accepts for example != or == but will not accept either < or > conditions.
if frequnecyInput > zeroValue {
Text("Length : \(number / (frequnecyInput ?? 0.00))")
.font(.largeTitle)
.color(Color.gray)
.frame(width: 300.0, height: 40.0)
.shadow(radius: 8.0)
.padding()
}
Above code will not compile.
if frequnecyInput != zeroValue {
Text("Length : \(number / (frequnecyInput ?? 0.00))")
.font(.largeTitle)
.color(Color.gray)
.frame(width: 300.0, height: 40.0)
.shadow(radius: 8.0)
.padding()
}
Above code will compile.
What am I doing wrong?
Cheers.
I'd ask what error message you are getting, but it doesn't matter, since compile errors with SwiftUI (at least in beta3) are unhelpful and usually just red herrings.
I'm guessing that since you have a frequnecyInput ?? 0.00 statement that frequnecyInput is a Optional<Double>, in which case != is a legal statement but < is not ("Binary operator '>' cannot be applied to operands of type 'Double?' and 'Double'").
For the record, the following compiles and runs for me:
import SwiftUI
struct ContentView : View {
private var frequnecyInput: Double? = 1.0
private var zeroValue: Double? = 0.0
private var number: Double = 3.0
var body: some View {
if (frequnecyInput ?? 0.0) > (zeroValue ?? 0.0) {
return AnyView(Text("Length : \(number / (frequnecyInput ?? 0.00))")
.font(.largeTitle)
.color(Color.gray)
.frame(width: 300.0, height: 40.0)
.shadow(radius: 8.0)
.padding())
} else {
return AnyView(Text("None"))
}
}
}
Hopefully the next beta (which will be released tomorrow) will improve the compiler error messages somewhat.
Related
Im fairly new to Swift and I'm trying to produce a HStack (that will be used in a progress bar) of element and to be able to add elements with a button.
Im not sure if I should use a variable in the ForEach(1..<Variable) section or use another method. Here is the code I have so far but it did not work.
struct ContentView: View {
#State var fill : CGFloat = 0
#State var NumberOfCircles : Int = 0
var body: some View {
HStack(spacing:100) {
ForEach(0..<NumberOfCircles){ _ in
MyShape()
}
Button(action: {NumberOfCircles = 5}, label: {
Text("Button")
})
}
ForEach in SwiftUI needs a constant range to loop over. However,
as the error suggests, if you conform to Identifiable or use ForEach(_:id:content:) and provide an explicit id it is happy. So try this:
struct ContentView: View {
#State var fill: CGFloat = 0
#State var NumberOfCircles: Int = 0
var body: some View {
HStack(spacing: 20) {
ForEach(0..<NumberOfCircles, id: \.self){ _ in // <-- here
MyShape()
}
Button(action: {NumberOfCircles = 5}){
Text("Button")
}
}
}
}
I'm not sure what's your problem, but I tested this code and it works:
struct ContentView: View {
#State var numberOfCircles = 1
var body: some View {
VStack {
HStack {
ForEach(0..<numberOfCircles, id:\.self) { _ in
Circle()
.frame(width: 30, height: 30)
}
}
Button { numberOfCircles = 5 } label: {
Text("Add Circles")
}
}
}
}
Btw, naming convention for variables in Swift is camelCase. That means that declaring a variable you should name it numberOfCircles , not NumberOfCircles . The first uppercase letter is reserved for naming Classes, Structs and Protocols.
My Swift-Class defines an initWith.. method by the following code
convenience init(controlType: ApplePencilControlType) {
self.init(frame: CGRect())
type = controlType
self.frame = self.controlFrame
if type == .zoom {
zoomSlider = UISlider(frame: CGRect(x: 10, y: 10, width: 100, height: 20))
if let slider = zoomSlider {
self.addSubview(slider)
}
}
else if type == .toLeft || type == .toRight {
imageView = UIImageView(frame: CGRect(x: 5, y: 5, width: 20, height: 20))
if let imgView = imageView {
if let img = type.image {
imgView.image = img
}
self.addSubview(imgView)
}
}
}
Trying to call this method by the following Objective-C Code makes Xcode show up an error.
- (void)presentOrHidePencilControls {
self.apToLeft = [[ApplePencilControl alloc] initWithControlType:ApplePencilControlTypeToLeft];
}
The error is No visible #interface for 'ApplePencilControl' declares the selector 'initWithControlType:'
What have I to do, so i can call this initializer from Objective-C? The "Project/Modul-Swift.h" is already imported.
I had to insert #objc and : Int to my enum definition in the same class.
I have a frameless QQuickWindow, and I want to move it with the mouse by dragging. Before trying in my big application, I have created a simple test application to try what I found here, using cursor position from C++ class to avoid problems from QML:
http://www.tickanswer.com/solved/5390888353/dragging-frameless-window-jiggles-in-qml
But I failed with the code below. When I press over the red RECT and move the mouse, my yellow rect (root RECT) moves, but only inside the original size it had (in this case, 500x500)... What am I doing wrong?
Thanks in advance
In my main.cpp:
int main(int argc, char *argv[])
{
QtQuickControlsApplication a(argc, argv);
QQuickView* pView = new QQuickView();
CursorPosProvider mousePosProvider;
pView->rootContext()->setContextProperty("mousePosition", &mousePosProvider);
pView->setSource(QUrl("qrc:/Test.qml"));
pView->setFlags(Qt::FramelessWindowHint);
pView->show();
return a.exec();
}
Test.qml:
import QtQuick 2.0
Rectangle {
id: myWindow
width: 500; height: 500
color: "yellow"
Rectangle {
anchors.centerIn: parent
width: 200; height: 200
color: "red"
MouseArea {
id: titleBarMouseRegion
property var clickPos
anchors.fill: parent
onPressed: clickPos = { x: mousePosition.cursorPos().x, y: mousePosition.cursorPos().y }
onPositionChanged: {
myWindow.x = mousePosition.cursorPos().x - clickPos.x
myWindow.y = mousePosition.cursorPos().y - clickPos.y
}
}
}
}
cursorprovider.h:
#ifndef CURSORPOSPROVIDER_H
#define CURSORPOSPROVIDER_H
#include <QObject>
#include <QPointF>
#include <QCursor>
class CursorPosProvider : public QObject
{
Q_OBJECT
public:
explicit CursorPosProvider(QObject *parent = nullptr) : QObject(parent)
{
}
virtual ~CursorPosProvider() = default;
Q_INVOKABLE QPointF cursorPos()
{
return QCursor::pos();
}
};
#endif // CURSORPOSPROVIDER_H
I wrote this example and I see no jiggle (running on Linux)
ApplicationWindow {
id: iWindow
visible: true
title: "My title"
color: "gray"
width: 500
height: 500
MouseArea{
id: iMouseArea
property int prevX: 0
property int prevY: 0
anchors.fill: parent
onPressed: {prevX=mouse.x; prevY=mouse.y}
onPositionChanged:{
var deltaX = mouse.x - prevX;
iWindow.x += deltaX;
prevX = mouse.x - deltaX;
var deltaY = mouse.y - prevY
iWindow.y += deltaY;
prevY = mouse.y - deltaY;
}
}
}
I have changed the structure, I have used a QQuickWidget with a QML inside, and now I have what I wanted. Here is my code in case anyone needs something similar
main.cpp
...
MovableWidget *view = new MovableWidget;
view->setSource(QUrl("qrc:/Test.qml"));
view->setWindowFlags(Qt::FramelessWindowHint);
view->show();
...
Test.qml
import QtQuick 2.0
Rectangle {
id: myWindow
width: 500; height: 500
color: "yellow"
Rectangle {
anchors.centerIn: parent
width: 200; height: 200
color: "red"
}
}
MovableWidget.cpp
#include "movableWidget.h"
#include <QMouseEvent>
// ****************************************************************************
MovableWidget::MovableWidget(QWidget *parent)
: QQuickWidget(parent),
m_previousPos(0,0)
{
installEventFilter(this);
}
// ****************************************************************************
bool MovableWidget::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseButtonPress)
{
m_previousPos = QCursor:os();
}
else if (event->type() == QEvent::MouseMove)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
if(mouseEvent->buttons() == Qt::LeftButton)
{
QPoint offset = m_previousPos - QCursor:os();
m_previousPos = QCursor:os();
move(pos() - offset);
}
}
return false;
}
I have update my Project to Swift3 in Xcode 8 and it comes this error but I have no idea what I can make there. I have already search in google but nothing founded.
Have anyone an Idea what I can make ?
Here the Error:
Method 'collectionViewContentSize()' with Objective-C selector 'collectionViewContentSize' conflicts with getter for 'collectionViewContentSize' from superclass 'UICollectionViewLayout' with the same Objective-C selector
public func collectionViewContentSize() -> CGSize {
let numberOfSections = collectionView?.numberOfSections
if numberOfSections == 0 {
return CGSize.zero
}
var contentSize = collectionView?.bounds.size
contentSize?.height = CGFloat(columnHeights[0])
return contentSize!
}
I had something similar but I was overriding collectionViewContentSize()
override func collectionViewContentSize() -> CGSize {
let collection = collectionView!
let width = collection.bounds.size.width
let height = max(posYColumn1, posYColumn2)
return CGSize(width: width, height: height)
}
I Downloaded XCode 8 beta 4 today and have had to change it to:
override var collectionViewContentSize: CGSize {
let collection = collectionView!
let width = collection.bounds.size.width
let height = max(posYColumn1, posYColumn2)
return CGSize(width: width, height: height)
}
I'm trying to convert this example here:
https://github.com/NilStack/NKWatchChart
to swift2-code. I'm having problems with exactly this part:
data01.getData = ^(NSUInteger index) {
CGFloat yValue = [data01Array[index] floatValue];
return [NKLineChartDataItem dataItemWithY:yValue];
};
getData is defined as follows:
public class NKLineChartData : NSObject {
public var color: UIColor!
public var alpha: CGFloat
public var itemCount: UInt
public var getData: LCLineChartDataGetter!
The LCLineChartDataGetter is a type alias:
public typealias LCLineChartDataGetter = (UInt) -> NKLineChartDataItem!
I'm pretty new to objective-c and swift, so maybe someone can point me to how the assignment can be done using swift!
I found the solution myself. The equivalent in Swift is:
data01.getData = {(index : UInt) -> NKLineChartDataItem in
let yValue : CGFloat = CGFloat(data01Array[Int(index)] as! NSNumber)
return NKLineChartDataItem.init(y: yValue)
}
Maybe someone has a better/shorter solution but the above seems to work ;)
The thing being assigned to getData in Obj-C is a block that takes an integer parameter and returns a NKLineChartDataItem. (Check something like http://goshdarnblocksyntax.com if you need help remembering these.)
In Swift, the formal syntax for the corresponding closure looks like this:
data01.getData = { (index: UInt) -> NKLineChartDataItem! in
// body
}
But you can also use type inference to shorten it:
data01.getData = { index in
// body
}
Looking at more of the example from the NKWatchChart readme you linked to:
NSArray * data01Array = #[#60.1, #160.1, #126.4, #0.0, #186.2, #127.2, #176.2];
NKLineChartData *data01 = [NKLineChartData new];
data01.color = NKGreen;
data01.alpha = 0.9f;
data01.itemCount = data01Array.count;
data01.inflexionPointStyle = NKLineChartPointStyleTriangle;
data01.getData = ^(NSUInteger index) {
CGFloat yValue = [data01Array[index] floatValue];
return [NKLineChartDataItem dataItemWithY:yValue];
};
You can probably shorten this even more through native Swift types:
let data01Array: [CGFloat] = [60.1, 160.1, 126.4, 0.0, 186.2, 127.2, 176.2]
let data01 = NKLineChartData()
data01.color = NKGreen
data01.alpha = 0.9
data01.itemCount = data01Array.count
data01.inflexionPointStyle = .Triangle;
data01.getData = { NKLineChartDataItem(y: data01Array[$0]) }
You don't need to convert swift to objective-c to make it run in your project. Just drag the swift into your project and Xcode will automatically generate a bridging header for you