I want to use static variables for APIrequests. This API runs with Get Method and I have to run with some parameters with dynamically. So How can I change this parameters ?
For Example :
static let productDetail = "http:.../ProductDetail?productID=101&subNo=148"
I want to reach with XClass.productDetail also change productID=101 and subNo=148 with needed parameters.
You could make it a function and then pass the productID and subNo you want as parameters:
static func productDetail(productID: Int, subNo: Int) -> String {
return "http:.../ProductDetail?productID=\(productID)&subNo=\(subNo)"
}
If you have more parameters, you could also pass them as dictionary:
func productDetail(parameters: [String: String]) -> String {
var str = "http:.../ProductDetail?"
parameters.forEach {
str.append("\($0.key)=\($0.value)&")
}
str = String(str.dropLast()) // drops last '&' char
return str
}
Usage:
productDetail(parameters: ["productID": "108", "subNo": "93"])
// returns "http:.../ProductDetail?productID=108&subNo=93"
Related
I need to pass a compose content parameter in data class. For example a button can render when added into this content.
data class ContentData {
val content: #Composable ()-> Unit
}
This is working but when I get the app background I am getting parcelable exception. How to solve this problem.
One possible explanation I think that will occur related with a parcelable error, happens if you try to pass such object between activities as extras through Intent. Consider not use Composable as parameters in objects. Instead, try to represent the parameters of your Composable with a model which contains the parameters.
// your compose function
#Composable
fun Item(content: String = "Default", padding: Dp){
// ...
}
// Ui Model which contains your data (instead of have a weird composable reference) as a parcelable.
data class ContentData(
val content: String = "Default",
val paddingRaw: Int = 0
) : Parcelable {
constructor(parcel: Parcel) : this(
parcel.readString().orEmpty(),
parcel.readInt()
) {
}
override fun writeToParcel(parcel: Parcel, flags: Int) {
parcel.writeString(content)
parcel.writeInt(paddingRaw)
}
override fun describeContents(): Int {
return 0
}
companion object CREATOR : Parcelable.Creator<ContentData> {
override fun createFromParcel(parcel: Parcel): ContentData {
return ContentData(parcel)
}
override fun newArray(size: Int): Array<ContentData?> {
return arrayOfNulls(size)
}
}
}
// Example if you need the model between activities through the intent as an extra.
val data = ContentData("your content", 11)
val intent = Intent().apply {
putExtra("keyContentData", data)
}
//The way of get and use your model.
val contentData = intent.extras?.get("keyContentData") as ContentData
#Composable
fun ParentComponent(){
// ...
Item(
contentData?.content.orEmpty(),
contentData?.paddingRaw?.dp ?: 0.dp
)
// ...
}
How do I write a Function that map's an object to a csv string?
public Function<Flux<CleanAccessLogLine>, Flux<String>> toCsv() {
...
}
Simply use the Flux.map function: https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Flux.html#map-java.util.function.Function-
public Function<Flux<CleanAccessLogLine>, Flux<String>> toCsv() {
return input -> input.map(line -> toCsv(line));
}
String toCsv(CleanAccessLogLine line) {
// logic that converts the CleanAccessLogLine into a CSV String
}
I am adding an extension for replacing empty string with a constant value like:
extension String {
func checkIfEmpty() -> String {
return self.isEmpty ? "--------":self
}
}
and also tried the following:
extension String {
var checkIfEmpty: String {
return self.isEmpty ? "--------":self
}
}
using it as:
var string1 = ""
var string2 = "Not empty"
print("\(string1.checkIfEmpty)")
print("\(string2.checkIfEmpty)")
print("\(string1.checkIfEmpty())")
print("\(string2.checkIfEmpty())")
but none of them are working. The error says:
Value of type 'String' has no member 'checkIfEmpty'
I'm using iOS 11, Swift 4 and Xcode Version 9.2.
use
extension String {
func checkIfEmpty() -> String {
return self.isEmpty ? "--------":self
}
}
and call it like so (notice the () ):
print("\(string1.checkIfEmpty())")
print("\(string2.checkIfEmpty())")
It is perfectly okay. I was trying it in another target that's why having problem.
I am writing a struct in Swift:
struct LevelDictionary {
let kNumberOfSegments: Int = 10
static func loadLevelData() -> NSDictionary {
for var segmentNumber = 0; segmentNumber < kNumberOfSegments; ++segmentNumber {
//My code here
}
return dictionary
}
}
For some reason I get an error on compiling: Instance member 'kNumberOfSegments' cannot be used on type 'LevelDictionary'. What am I missing? I get the same error when I set up LevelDictionary as a Class.
loadLevelData() is a static function which is called on "class" level
LevelDictionary.loadLevelData()
To use kNumberOfSegments in the static function it must be static as well
static let kNumberOfSegments: Int = 10
The direct answer to your question is that you can't use a property in class scope.
A different answer is that you seem to want a static function that returns a dictionary after doing something a certain number of times; which is why you have kNumberOfSegments in the first place. But do you really need to have a variable for something that you aren't going to use again. Another way to do this is to have a default variable in your class method:
struct LevelDictionary {
static func loadLevelData(numberOfSegments: Int = 10) -> NSDictionary {
for segment in 0 ..< numberOfSegments {
// your code here
}
return dictionary
}
}
Now you can call the method without an argument to use the default
let dictionary = LevelDictionary.loadLevelData() // Will use 10 segments
Or you can use a parameter to override the default
let dictianary = LevelDictionary.loadLevelData(20) // Will use 20 segments
You can't use instance member variables/constants inside the static function. (In terms of Objective C you can't use instance member objects inside class function)
Either you should declare the kNumberOfSegments as static or make that function as non-static. I prefer the first option,
struct LevelDictionary
{
static let kNumberOfSegments: Int = 10
static func loadLevelData() -> NSDictionary
{
for var segmentNumber = 0; segmentNumber < kNumberOfSegments; ++segmentNumber
{
//My code here
}
return dictionary
}
}
In an application I've written I have a process that parses a large amount of data from Core-Data and displays it to a graph. While doing this processing I also end up writing the data out to a CSV File. I created a separate class called CSVLine which assists with the creation of the CSV file.
For my test case of 140k recorded my Objective-C code takes aprox 12 seconds to run. After "migrating" the class over to swift It now takes somewhere between 280-360 seconds to run. Obviously I've done something terrible.
Using Instruments I was able to identify the "slow" method and I was wondering if I've done something clear in SWIFT to cause the issue.
Objc
- (void)newLine {
// NSLog(#"Appending %#", self.csvString);
[outData appendData:[self csvData] ];
[self clear];
}
- (void)clear {
// Erase every single value
for (NSUInteger i = 0; i < [values count]; i ++) {
values[i] = #"";
}
}
Swift
func newLine() {
outData.appendData(csvData())
clear()
}
// Clear out the Array
func clear() {
for (var i = 0; i < values.count; i++) {
values[i] = ""
}
}
I'm working with various types of data that are all being written to a single CSV file so there are many blank lines. To accommodate for this I designed this class so that it has an array of keys and an array of values. The keys store the "column" names for the CSV file and values will store either a blank or a value for the index of the key for that data element.
Example:
Keys = [speed,heading,lat,lon]
values might be [200,300,"",""]
or ["","","38.553","25.2256"]
Once I'm done with a line i will write a comma joined list of the values into an internal data structure and clear out the line (erase all the items in the values array). This seems to be where the slowdown is with the swift class. Is there something blatantly "slow" i'm doing when i zero out my array?
Full Swift Class
#objc class CSVLineSwift : NSObject {
// Define Arrays
var keys: [String] = [String]()
var values: [String] = [String]()
var outData : NSMutableData = NSMutableData()
override init() {
}
// Singelton Operator - Thread Safe :: http://code.martinrue.com/posts/the-singleton-pattern-in-swift
class var instance : CSVLineSwift {
// Computed Property
struct Static {
static var instance : CSVLineSwift?
static var token: dispatch_once_t = 0
}
dispatch_once(&Static.token) {
Static.instance = CSVLineSwift();
}
return Static.instance!
}
// Erase existing Data
func newFile() {
outData = NSMutableData();
outData.appendData(headerData())
}
func csvString() -> String {
return ",".join(values)
}
func csvData() -> NSData {
let string = csvString()
let data = string.dataUsingEncoding(NSUTF8StringEncoding)
return data!
}
func addField(field : String) {
keys.append(field)
values.append("")
}
func setValueForKey(value:String, key:String) {
if let index = find(keys, key) {
values[index] = value
} else {
print( "ERROR -- There was no key: \(key) in the header Array")
}
}
func headerString() -> String {
return ",".join(keys)
}
func headerData() -> NSData {
return headerString().dataUsingEncoding(NSUTF8StringEncoding)!
}
func newLine() {
outData.appendData(csvData())
clear()
}
// Clear out the Array
func clear() {
for (var i = 0; i < values.count; i++) {
values[i] = ""
}
}
func writeToFile(fileName : String) {
outData.writeToFile(fileName, atomically: true)
}
}
Be sure that Swift's optimization level in Build Settings is not -Onone. In my experience, it is orders of magnitude slower than -O. (-O is also the default for 'release', so alternatively you could simply build for release, as already suggested.) As for 'zeroing out' the array, it might be faster (although I do not know) to simply re-initialize the array with a repeated value:
values = [String](count: values.count, repeatedValue: "")
Or if you know you will be appending the new values as you go along, and are not bound to using the indices, you could call:
values.removeAll(keepCapacity: true)
And add the new values with values.append() rather than at indices.
It appears my issues were due to a debug build. In debug build there is no optimization. Once you do a run build the optimization kicks in and things run MUCH MUCH faster....
Similar to the answer posted here: Is Swift really slow at dealing with numbers?