I am relatively new to swift. I made a simple text-based calculator in swift using NSExpression. I have a problem, however: this text-based calculator calculates the first expression typed into it perfectly every time (expressions from 2+4 to 9*7-1/3*2+1), but the second time, the outputted result is always just the same result as the first one (it won't calculate again). Here is the basics of my code:
I call it from a view controller and make a result label's text equal to the result found in the swift file far below:
x.savetextfinal = calculatortextfield.text! // Variable x.savetextfinal, created elsewhere in a struct, is assigned to the user's input.
// Now the magic happens in calculatormath.swift (see below)
print("this is the result \(z.nsexpress2)")
equalsresultlabel.text = "Result is (z.nsexpress2)."
Then this block of code, found in a separate swift file, seems to me to occur. It uses NSExpression to convert the expression from a string to an NSExpression, then creates a variable and assigns the result "result" of the NSExpression "mathExpression" to it as a string.
import Foundation
var nsexpress:String = String(x.savetextfinal)
var mathExpression = NSExpression(format: nsexpress)
var result:Float = Float((mathExpression.expressionValueWithObject(nil, context: nil) as? NSNumber)!)
struct calculatoranswer {
var nsexpress2:String = String(result)
}
var z = calculatoranswer()
Any ideas why this calculator will not calculate an expression twice will be much appreciated! Thanks.
All I had to do was put all of my calculating code in a function and call it in my view controller. Everything in my calculating swift file was put in a function, which I put inside a struct, and I called the function. Everything worked as planned, and I had my calculator. Structs and functions, not too hard even for beginners like me.
Related
I want to make an app that has 2 textfields, 4 buttons and a Text view. 1 button that clears the content of the first textfield and another button that inputs the current time rounded to the nearest 4 and the Text view to display the total time in minutes. Same with the other textfield. It's an app to calculate the total time spent on something in minutes.
I also want to limit the amount of possible insertable characters to 5 as a time has a maximum of 5 characters as in "15:00". I have been able to make an observable object:
class TextFieldManager: ObservableObject {
let characterLimit = 5
#Published var userInput = "" {
didSet {
// Limit the max length of the field
if userInput.count > characterLimit {
userInput = String(userInput.prefix(characterLimit))
} else if userInput.count >= 4 {
// call the setTotalTime func or something to set totalTime
}
}
}
}
which works really well.
I am also able to clear the textfield and set the current time rounded to the nearest 5, but i am unable to limit the characters to 5 AND have the buttons do something at the same time.
So right now it's either being able to:
- Limit characters to a maximum of 5
OR being able to:
clear textfield with a button
input time now rounded to nearest 5 into textfield with a button.
If i go with the observable object method, when i have this above the body block of my ContentView:
#ObservedObject var startTimeManager = TextFieldManager()
#ObservedObject var endTimeManager = TextFieldManager()
and this inside the body for the textfields:
TextField("hh:mm", text: $startTimeManager.userInput)
TextField("hh:mm", text: $endTimeManager.userInput)
and the TextFieldManager class as shown above, than now i don't know how to get the value of the Textfield anymore.
If inside the input the current time button i try to set the time by doing
$startTimeManager.userInput = "whatever the current time is"
i get an error saying that i can't change the value of a binding<String> type something something. Likewise i also can't clear the textfield in the same way.
Also i would like to call a function inside this part:
} else if userInput.count >= characterLimit {
// call the setTotalTime func or something to set totalTime
}
I have a Functions.swift file where both the TextFieldManager class is and my function that i want to call, but if i try to call a function inside here, it says that the function doesn't exist? And inside the function i again would like to have access to the textfield values at the time of the call, but i don't know how to read the value of the textfields from inside the function.
I hope i am making sense and that someone is able to help me, or point me in the right direction. I made the same app for android (android studio), windows (python3) and Mac (python3), but this iphone and Xcode thing really doesn't want to work. I have watched a bunch of tutorial videos and guides, but none are trying to do what i am trying to do. Like i said i can get either to work, but never together and in both cases i am unable to somehow access the textfield values inside the function. I feel like i should be so close, but something is not coming together for me in my head.
Also while i'm at it, in Python 3 to catch all errors and let them pass silently i can do:
Try:
break_my_stuff = int("Break my stuff)"
ignore_some_more_stuff = int("ignore some more stuff)"
etc.
etc.
except Exception:
# catch silently and do nothing
pass
Is there something similar in swift, because
do {
breakMyStuff = whatever might make something break in swift
ignoreSomeMoreStuff = whatever might make something break in swift
etc.
etc.
} catch {
// do nothing and pass silently
}
doesn't work because it needs something to try and i wasn't able to try a complete section like i can with Python.
If inside the input the current time button i try to set the time by doing
$startTimeManager.userInput = "whatever the current time is"
you don't need binding in this case, just assign property in regular way
self.startTimeManager.userInput = "whatever the current time is"
I have a Lua function where I build a table of value and attempt to add it to a global table with a named key.
The key name is pulled from the function arguments. Basically, it's a filename, and I'm pairing it up with data about the file.
Unfortunately, the global table always comes back nil. Here's my code: (let me know if you need to see more)
(Commented parts are other attempts, although many attempts have been deleted already)
Animator = Class{}
function Animator:init(atlasfile, stringatlasfriendlyname, totalanimationstates, numberofframesperstate, booleanstatictilesize)
-- Define the Animator's operation mode. Either static tile size or variable.
if booleanstatictilesize ~= false then
self.isTileSizeStatic = true
else
self.isTileSizeStatic = false
end
-- Define the total animation states (walking left, walking right, up down, etc.)
-- And then the total frames per state.
self.numAnimationStates = totalanimationstates or 1
self.numAnimationFrames = numberofframesperstate or 2
-- Assign the actual atlas file and give it a programmer-friendly name.
self.atlasname = stringatlasfriendlyname or removeFileExtension(atlasfile, 'animation')
generateAnimationQuads(atlasfile, self.atlasname, self.numAnimationStates, self.numAnimationFrames)
end
function generateAnimationQuads(atlasfile, atlasfriendlyname, states, frames)
spriteWidthDivider = atlasfile:getWidth() / frames
spriteHeightDivider = atlasfile:getHeight() / states
animationQuadArray = generateQuads(atlasfile, spriteWidthDivider, spriteHeightDivider)
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
--gAnimationSets[#gAnimationSets+1] = atlasfriendlyname
gAnimationSets[atlasfriendlyname] = animationSetValues
--table.insert(gAnimationSets, atlasfriendlyname)
end
Note: when using print(atlasfriendlyname) and print(animationSetValues), neither are empty or nil. They both contain values.
For some reason, the line(s) that assign the key pair to gAnimationSets does not work.
gAnimationSets is defined a single time at the top of the program in main.lua, using
gAnimationSets = {}
Animator class is called during the init() function of a character class called Bug. And the Bug class is initialized in the init() function of StartState, which extends from BaseState, which simply defines dummy init(), enter(), update() etc. functions.
StartState is invoked in main.lua using the StateMachine class, where it is passed into StateMachine as a value of a global table declared in main.lua.
gAnimationSets is declared after the table of states and before invoking the state.
This is using the Love2D engine.
Sorry that I came here for help, I've been picking away at this for hours.
Edit: more testing.
Trying to print the animationQuadArray at the index gTextures['buganimation'] always returns nil. Huh?
Here's gTextures in Main.lua
gTextures = {
['background'] = love.graphics.newImage('graphics/background.png'),
['main'] = love.graphics.newImage('graphics/breakout.png'),
['arrows'] = love.graphics.newImage('graphics/arrows.png'),
['hearts'] = love.graphics.newImage('graphics/hearts.png'),
['particle'] = love.graphics.newImage('graphics/particle.png'),
['buganimation'] = love.graphics.newImage('graphics/buganimation.png')
}
Attempting to return gTextures['buganimation'] returns a file value as normal. It's not empty.
My brain is so fried right now I can't even remember why I came to edit this. I can't remember.
Global table in Main.lua, all other functions can't access it.
print(gTextures['buganimation']) works inside the function in question. So gTextures is absolutely accessible.
Table isn't empty. AnimationSetValues is not empty.
I'm adding second answer because both are correct in context.
I ended up switching IDE's to VS Code and now the original one works.
I was originally using Eclipse LDT with a Love2D interpreter and in that environment, my original answer is correct, but in VS Code, the original is also correct.
So Dimitry was right, they are equivalent, but something about my actual Eclipse setup was not allowing that syntax to work.
I switched to VS Code after I had another strange syntax problem with the interpreter where goto syntax was not recognized and gave a persistent error. The interpreter thought goto was the name of a variable.
So I switched, and now both things are fixed. I guess I just won't use LDT for now.
Solution: Lua syntax. Brain Fry Syndrome
I wrote:
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
Should be:
animationSetValues = {['atlasfile']=atlasfile, ['atlasarray']=animationQuadArray, ['width']=spriteWidthDivider, ['height']=spriteHeightDivider}
Edit: I'm fully aware of how to use answers. This was posted here to reserve my spot for an answer so I could edit it later when I returned back home, which is exactly what I'm doing right now. I'll keep the old post for archival purposes.
Original:
I solved it. I apologize for not posting the solution right now. My brain is melted into gravy.
I will post it tomorrow. Just wanted to "answer" saying no need to help. Solved it.
Solution is basically, "oh it's just one of those Lua things". Wonderful. I'm having so much fun with this language - you can tell by my blank expression.
From the language without line endings or brackets, but forced print parentheses... ugh. I'm going back to C# when this class is done.
I understand how I could, for example look at one element in a table, but what's the correct way to simply iterate through all the elements, however many are found, to for example tap on them?
let indexFromTheQuery = tables.staticTexts.elementBoundByIndex(2)
Okay I succeeded in figuring out the simple syntax. I have just started working with Swift and so it took me sleeping on it to think of the answer.
This code works:
var elementLabels = [String]()
for i in 0..<tables.staticTexts.count {
elementLabels.append (tables.staticTexts.elementBoundByIndex(i).label)
}
print (elementLabels)
My guess is the answer is there is no way to do so.
The reason is because of my experience with one of the critical iOS components while making a number of UI tests: UIDatePicker.
If you record a test where you get the page up and then you spin the picker, you will notice that the commands are all non-specific and are screen related. In the case of the picker, however, community requests resulted in the addition of a method for doing tests: How to select a picker view item in an iOS UI test in Xcode?.
Maybe you can add a helper method to whatever controller contains this table. Also, keep in mind that you can easily add methods without polluting the class interface by defining them as extensions that are in test scope only.
For Xcode 11.2.1, SwiftUI and swift 5 based app, the following code works for testing a list, each element in this case appears as a button in the test code. The table is set up like this (for each row) :
NavigationLink(destination: TopicDetail(name: "Topic name", longDesc: "A description")) {
TopicRow(thisTopic: top).accessibility(identifier: "newTopicRow_\(top.name!)")
}
Then I catch the members of the table by getting the buttons into an array:
let myTable = app.tables.matching(identifier: "newTopicTable")
var elementLabels = [String]()
for i in 0..<myTable.buttons.count {
elementLabels.append (tablesQuery.buttons.element(boundBy: i).label)
}
print (elementLabels)
Finally, I deleted each member of the table by selecting the detail view where I have a delete button, again with
.accessibility(identifier: "deleteTopic"
I wanted to delete all members of the table:
for topicLabel in elementLabels {
let myButton = app.buttons[topicLabel]
myButton.firstMatch.tap()
app.buttons["deleteTopic"].tap()
}
So I have this crazy problem with comparing 2 strings in ActionScript 2.0
I have a global variable which holds some text (usually it is "statistic") from xml feed
_root.var_name = fields.firstChild.attributes.value;
when I trace() it it gives me the expected message
trace(_root.var_name); // echoes "statistik"
and when I try to use it in conditional statement the rest of code is not being executed because comparing :
if(_root.overskrift == "statistik"){
//do stuff
}
returns false!
I tried also with:
if(_root.overskrift.equals("statistik"))
but with the same result.
Any input will be appreciated.
Years later but on a legacy project I had the same problem and the solution was in a comment to this unanswered question. So let's make it an anwer:
Where var a:String="some harmless but in my case long string" and var b:String="some harmless but in my case long string" but (a==b) -> false the following works just fine: (a.indexOf(b)>=0) -> true. If the String were not found indexOf would give -1. Why the actual string comparison fails I coudn't figure out either. AS2 is ancient and almost obsolete...
I'm trying to get a handle on how OOP is done in Lua, and I thought I had a simple way to do it but it isn't working and I'm just not seeing the reason. Here's what I'm trying:
Person = { };
function Person:newPerson(inName)
print(inName);
p = { };
p.myName = inName;
function p:sayHello()
print ("Hello, my name is " .. self.myName);
end
return p;
end
Frank = Person.newPerson("Frank");
Frank:sayHello();
FYI, I'm working with the Corona SDK, although I am assuming that doesn't make a difference (except that's where print() comes from I believe). In any case, the part that's killing me is that inName is nil as reported by print(inName)... therefore, myName is obviously set to nil so calls to sayHello() fail (although they work fine if I hardcode a value for myName, which leads me to think the basic structure I'm trying is sound, but I've got to be missing something simple). It looks, as far as I can tell, like the value of inName is not being set when newPerson() is called, but I can't for the life of me figure out why; I don't see why it's not just like any other function call.
Any help would be appreciated. Thanks!
Remember that this:
function Person:newPerson(inName)
Is equivalent to this:
function Person.newPerson(self, inName)
Therefore, when you do this:
Person.newPerson("Frank");
You are passing one parameter to a function that expects two. You probably don't want newPerson to be created with :.
Try
Frank = Person:newPerson("Frank");