For my math question app I have two random numbers generated then I have 4 buttons as answers. I want to check the answer if the user pushes the right button but it seems not to work.
num1 and num2 are the labels which the random numbers are generated in so technically
num1.text = "(randomnum1)"
and num2.text = "(randomnum2)" Thanks.
I have the following code under button1 IBaction
var sum = (num1) + (num2)
if btn1.titleLabel = (sum){
check.text = "right"
}
Maybe you should do some convert before you add num1 and num2. (convert strings to integers before adding them up, also, you should convert string to integer fisrt when comparing sum and btn.titleLabel)
you have two options:
if btn1.titleLabel.toInt()! == sum
or
if btn1.titleLabel == String(sum)
consider the difference between = (assign) and == (is equal)
to assign a number to a label use
num1.text = "\(randomnum1)"
I recommend to use backing Int variables like randomnum1 to hold the random numbers which can used for the math for example
var randomnum1 = 0, randomnum2 = 0 // instance variables of the class
randomnum1 = randomFuntion()
randomnum2 = randomFuntion()
num1.text = String(randomnum1)
num2.text = String(randomnum2)
now the labels contain the string values of the random numbers, but you can do the math with the associated variables.
var sum = randomnum1 + randomnum2
after that you can check the result as mentioned above
if btn1.titleLabel == String(sum) {
check.text = "right"
}
Related
Based on straight SQL searches in a previous app, I am adding CoreData searching to a new app. These searches are in a custom dictionary db that the app contains; this function does the work:
public func wordMatcher (pad: Int, word: Array<String>, substitutes : Set<String> ) {
let context = CoreDataManager.shared.persistentContainer.viewContext
var query: Array<String>
var foundPositions : Set<Int> = []
var searchTerms : Array<String> = []
if word.count >= 4 {
for i in 0..<word.count {
for letter in substitutes {
query = word
query[i] = letter
searchTerms.append(query.joined())
let rq: NSFetchRequest<Word> = Word.fetchRequest()
rq.predicate = NSPredicate(format: "name LIKE %#", query.joined())
rq.fetchLimit = 1
do {
if try context.fetch(rq).count != 0 {
foundPositions.insert(i)
break
}
} catch {
}
}
// do aggregated searchTerms search here instead of individual searches?
}
}
}
The NSFetchRequest focuses on one permutation at a time. But I'm accumulating the search string fragments in the array searchTerms because I don't know if it would be more efficient to construct a single query connected with ORs, and I also don't know how to do that in CoreData.
The focus is on the positions in the original term word: I need to indicate if any given location has at least one of the substitutes as a valid fit. So to implement the aggregate searchTerms approach, a FetchRequest would have to happen for each location in the base term.
A second complication is the one referred to in the title of the question. I am using LIKE because the search term in the FetchRequest could be a substring in a longer word. However, the maximum number of letters is 11, and pad is the starting point of the original term in that field of 11 spaces.
So if pad is 3, then I would need to allow for 0..<pad preceding characters. And because there may be trailing characters, I would also want results with 0..<(11 - (pad + word.count)) alphabetic characters after the last letter in the search term.
Regex seems like one way to do this, but I haven't found a clear example of how to do this in this case, and especially with the multiple search terms (if that's the way to go). The limits of SQLite in the previous version forced constructing multiple queries with increasing numbers of "_" underscores to indicate the padding characters; that tended to really explode the number of queries.
BTW, substitutes is limited to an absolute maximum of 9 values, and in practice is usually below 5, so things are a little more manageable.
I would like to get a grip on this, and so if anyone can provide direction or examples that can make this a reasonably efficient function, the help is appreciated greatly.
EDIT:
I've realized that I need a result for each position in the target string, with cases where the leading and trailing spaces also may need to contain a substitute as well.
So I'm moving to this:
public func wordMatcher (pad: Int, word: Array<String>, substitutes : Set<String> ) {
let context = CoreDataManager.shared.persistentContainer.viewContext
var pad_ = pad
var query: Array<String>
var foundPositions : Set<Int> = []
let rq: NSFetchRequest<Word> = Word.fetchRequest()
rq.fetchLimit = 1
let subs = "[\(substitutes.joined())]"
// if word.count >= 4 { // because those locations will be blocked off anyway otherwise
let start = pad > 0 ? -1 : 0
let finish = 11 - (pad + word.count) > 0 ? word.count + 1 : word.count
for i in start..<finish {
query = word
var _pad = 11 - (pad + word.count)
if i == -1 {
query = Array(arrayLiteral: subs) + query
pad_ -= 1
} else if i > word.count {
query.append(subs)
_pad -= 1
} else {
pad_ = pad
query[i] = subs
}
let endPad = _pad > 0 ? "{0,\(_pad)}" : ""
let predMatch = ".\(query.joined())\(endPad)"
print(predMatch)
rq.predicate = NSPredicate(format:"position <= %# AND word MATCHES %#", pad_, predMatch)
do {
if try context.fetch(rq).count != 0 {
foundPositions.insert(i)
}
} catch {
}
// }
}
lFreq = foundPositions
}
This relies on a regex substitution, inserted into the original target string. What I'll have to find out is if this is fast enough at the edge cases, but it may not be critical even in the worst case.
predMatch will end up looking something like "ab[xyx]d{0,3}", and I think I can get rid of the position section by changing it to be "{0,2}ab[xyx]d{0,3}". But I guess I'm going to have to try to find out.
This question already has answers here:
How to split an Int to its individual digits?
(11 answers)
Closed 3 years ago.
say for example i have an Int var firstInt = 23 what i need is i want to assign the value of firstInt to two separate variables so the output would be var x = 2 and var y = 3. i tried converting the firstInt to a string like so var strFirstInt = String(firstInt) and wanted to assign the first index of the string to a different variable and the second index to another variable and convert them to Int but i couldn't pick the string by index. so any ideas how to do this?
You can use .compactMap from String like this :
let numberInt = 23
let digits = String(numberInt).compactMap{ $0.wholeNumberValue}
Response :
[2, 3]
And with this array, you put the first member to the first var and seconds to another:
var x = digits[0]
var y = digits[1]
print("The decade is \(x) and units is \(y)")
Response:
The decade is 2 and units is 3
Convert the firstInt to String and then to Array,
var firstInt = 23
let arr = Array(String(firstInt)).map({ String($0 )})
Next, get the elements as per the index from array, i.e.
var x = Int(arr[0])
var y = Int(arr[1])
Hi I am trying to use a UITextbox and restrict the number of characters input by the user to 10.
I have looked at using the below link,
Max length UITextField
My Questions,
1.Its not working as characters are depreciated in Swift 4 so the string.characters.count is throwing an error so what would be a workaround in Swift 4?
2.After the user enters his x number of characters, I want to make the reminders that is (limitlength - x) into empty spaces (ascii for space = 32 in decimal) so that reminder of the byte array is equal to dec 32.
I have tried doing this,
if let receivedData = rxCharacteristic?.value
let myByteArray = Array(receivedData) {
let b0 = myByteArray[0]
let b1 = myByteArray[1]
let b2 = myByteArray[2]
let b3 = myByteArray[3]
//Now reading data from textbox input
var userdata = textbox.text
let userdataarray: [UInt8] = Array(userdata!.utf8)
//I tried putting values into myByteArray as below
userdataarray[0] = myByteArray[0]
userdataarray[1] = myByteArray[1]
userdataarray[2] = myByteArray[2]
//The last value in myByteArray will remain unchanged so I'm not overwriting it
So from the question when I try to input textbox data less than its length its throwing an index out of range exception. But I went a little extreme to try the below code.
if(userdataarray[0] != 0 && userdataarray[0] != nil)
{
userdataarray[0] = myByteArray[0]
}
else
{
userdataarray[0] = 32 //Which is space in ascii
userdataarray[0] = myByteArray[0]
}
I don't think it worked but wanted to check on how its properly done?
If I understand your question correctly, then your trials are very much overenginering. In Swift you can just add characters to a String (as long as it is declared as var that is). This just boils down to
let orig = "Hello World"
var copy = orig
while copy.count < 15 {
copy.append(" ")
}
let dta = copy.data(using:.isoLatin1)!
let arr = Array(dta)
Since Swift is using some Unicode-encoding internally it is probably crucial to convert your String to data using a specific encoding if you plan to "directly" transfer it to some device that is limited to a certain character set. Still a lot less code than what you provided.
This is a follow up question to How to have 10 characters total and make sure at least one character from 4 different sets is used randomly
this is my code so far
let sets = ["ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghijklmnopqrstuvwxyz", "1234567890", "\"-/:;()$&#.,?!'[]{}#%^\\|~<>€£¥•.,"].map { Array($0.characters) }
var randoms = sets.map { $0.random }
while randoms.count < 10 {
randoms.append(sets.random.random)
}
var convertedElems = String()
let something = randoms.shuffled()
for key in something {
convertedElems = String(key)
}
uniqueRoomID.text = randoms.shuffled()
Im getting an error saying cannot convert [Element] to type "String"
So i tried a for loop but that only converts 1 at a time when its supposed to do all 10
my other question is i tried storing a character in a variable and then setting a text field.text equal to that variable and nothing happened
What am i doing wrong here
Your randoms.shuffled() is an array of Characters. You need to convert it back into a String.
Change this:
uniqueRoomID.text = randoms.shuffled()
to this:
uniqueRoomID.text = String(randoms.shuffled())
I have a long string (sometimes over 1000 characters) that I want to convert to an array of boolean values. And it needs to do this many times, very quickly.
let input: String = "001"
let output: [Bool] = [false, false, true]
My naive attempt was this:
input.characters.map { $0 == "1" }
But this is a lot slower than I'd like. My profiling has shown me that the map is where the slowdown is, but I'm not sure how much simpler I can make that.
I feel like this would be wicked fast without Swift's/ObjC's overhead. In C, I think this is a simple for loop where a byte of memory is compared to a constant, but I'm not sure what the functions or syntax is that I should be looking at.
Is there a way to do this much faster?
UPDATE:
I also tried a
output = []
for char in input.characters {
output.append(char == "1")
}
And it's about 15% faster. I'm hoping for a lot more than that.
This is faster:
// Algorithm 'A'
let input = "0101010110010101010"
var output = Array<Bool>(count: input.characters.count, repeatedValue: false)
for (index, char) in input.characters.enumerate() where char == "1" {
output[index] = true
}
Update: under input = "010101011010101001000100000011010101010101010101"
0.0741 / 0.0087, where this approach is faster that author's in 8.46 times. With bigger data correlation more positive.
Also, with using nulTerminatedUTF8 speed a little increased, but not always speed higher than algorithm A:
// Algorithm 'B'
let input = "10101010101011111110101000010100101001010101"
var output = Array<Bool>(count: input.nulTerminatedUTF8.count, repeatedValue: false)
for (index, code) in input.nulTerminatedUTF8.enumerate() where code == 49 {
output[index] = true
}
In result graph appears, with input length 2196, where first and last 0..1, A – second, B – third point.
A: 0.311sec, B: 0.304sec
import Foundation
let input:String = "010101011001010101001010101100101010100101010110010101010101011001010101001010101100101010100101010101011001010101001010101100101010100101010"
var start = clock()
var output = Array<Bool>(count: input.nulTerminatedUTF8.count, repeatedValue: false)
var index = 0
for val in input.nulTerminatedUTF8 {
if val != 49 {
output[index] = true
}
index+=1
}
var diff = clock() - start;
var msec = diff * 1000 / UInt(CLOCKS_PER_SEC);
print("Time taken \(Double(msec)/1000.0) seconds \(msec%1000) milliseconds");
This should be really fast. Try it out. For 010101011010101001000100000011010101010101010101 it takes 0.039 secs.
I would guess that this is as fast as possible:
let targ = Character("1")
let input: String = "001" // your real string goes here
let inputchars = Array(input.characters)
var output:[Bool] = Array.init(count: inputchars.count, repeatedValue: false)
inputchars.withUnsafeBufferPointer {
inputbuf in
output.withUnsafeMutableBufferPointer {
outputbuf in
var ptr1 = inputbuf.baseAddress
var ptr2 = outputbuf.baseAddress
for _ in 0..<inputbuf.count {
ptr2.memory = ptr1.memory == targ
ptr1 = ptr1.successor()
ptr2 = ptr2.successor()
}
}
}
// output now contains the result
The reason is that, thanks to the use of buffer pointers, we are simply cycling through contiguous memory, just like the way you cycle through a C array by incrementing its pointer. Thus, once we get past the initial setup, this should be as fast as it would be in C.
EDIT In an actual test, the time difference between the OP's original method and this one is the difference between
13.3660290241241
and
0.219357967376709
which is a pretty dramatic speed-up. I hasten to add, however, that I have excluded the initial set-up from the timing test. This line:
let inputchars = Array(input.characters)
...is particularly expensive.
This should be a little faster than the enumerate() where char == "1" version (0.557s for 500_000 alternating ones and zeros vs. 1.159s algorithm 'A' from diampiax)
let input = inputStr.utf8
let n = input.count
var output = [Bool](count: n, repeatedValue: false)
let one = UInt8(49) // 1
for (idx, char) in input.enumerate() {
if char == one { output[idx] = true }
}
but it's also a lot less readable ;-p
edit: both versions are slower than the map variant, maybe you forgot to compile with optimizations?
One more step should speed that up even more. Using reserveCapacity will resize the array once before the loops starts instead of trying to do it as the loop runs.
var output = [Bool]()
output.reserveCapacity(input.characters.count)
for char in input.characters {
output.append(char == "1")
}
Use withCString(_:) to retrieve a raw UnsafePointer<Int8>. Iterate over that and compare to 49 (ascii value of "1").
What about a more functional style? It's not fastest (47 ms), today, for sure...
import Cocoa
let start = clock()
let bools = [Bool](([Character] ("010101011001010101001010101100101010100101010110010101010101011001010101001010101100101010100101010101011001010101001010101100101010100101010".characters)).map({$0 == "1"}))
let msec = (clock() - start) * 1000 / UInt(CLOCKS_PER_SEC);
print("Time taken \(Double(msec)/1000.0) seconds \(msec%1000) milliseconds");
I need to some testing to be sure but I think one issue with many approaches given including the original map is that they need to iterate over the string to count the characters and then a second time to actually process the characters.
Have you tried:
let output = [Bool](input.characters.lazy.map { $0 == "1" })
This might only do a single iteration.
The other thing that could speed things up is if you can avoid using strings but instead use arrays of characters of an appropriate encoding (particularly if is more fixed size units (e.g. UTF16 or ASCII). Then then length lookup will be O(1) rather than O(n) and the iteration may be faster too
BTW always test performance with the optimiser enabled and never in the Playground because the performance characteristics are completely different, sometimes by a factor of 100.