Get JSON value to Array - ios

Question

I need to get the JSON value from MYSQL and display it in the table view. I have done PHP part to receive data but I have error with my XCODE. My data will store temperature, humidity and digital status (on off) of sensor. I have questions below:
How to get ON/OFF JSON value and store in Bool array?
How to get JSON value and store in Float array?
if JSON value is , how can I store value as 0 in XCODE?
class DataManager {
var nodenameArray: [String] = []
var nodeidArray: [String] = []
var tempArray: [Float] = []
var humArray: [Float] = []
var pirArray: [Bool] = []
var lightArray: [Bool] = []
var relayArray: [Bool] = []
var hallArray: [Bool] = []
var smokeArray: [Bool] = []
#objc func taskdo() {
self.nodenameArray = []
self.nodeidArray = []
self.tempArray = []
self.humArray = []
self.pirArray = []
self.lightArray = []
self.relayArray = []
self.hallArray = []
self.smokeArray = []
if userlogin == true {
let request = NSMutableURLRequest(url: NSURL(string: http://talectric.com/wp-admin/a_p/iot/read_all.php")! as URL)
request.httpMethod = "POST"
let postString = "username=\(username)&password=\(password)&authen=wdwfesf9329140dsvfxkciospdkm"
request.httpBody = postString.data(using: String.Encoding.utf8)
let task = URLSession.shared.dataTask(with: request as URLRequest) {
data, response, error in
if error != nil {
print("error=\(error!)")
return
} else {
do {
if let respondString = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary {
print(respondString)
if let nodedata = respondString.value(forKey: "nodedata") as? NSArray {
for node in nodedata{
if let nodeDict = node as? NSDictionary {
if let nodeid = nodeDict.value(forKey: "node_id") {
self.nodeidArray.insert(nodeid as! String, at: 0)
}
if let nodeid = nodeDict.value(forKey: "node_name") {
self.nodenameArray.insert(nodeid as! String, at: 0)
}
if let nodeid = nodeDict.value(forKey: "temp") {
self.tempArray.insert(Float(nodeid as! String)!, at: 0)
}
if let nodeid = nodeDict.value(forKey: "hum") {
print(nodeid)
self.humArray.insert(Float(Int(nodeid as! String)!), at: 0)
}
}
}
}
}
print(self.nodenameArray)
print(self.nodeidArray)
print(self.tempArray)
print(self.humArray)
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "load"), object: nil)
}
catch let error as NSError {
print(error.debugDescription)
}
}
}
task.resume()
}
}
}
below is the respond:
{
nodedata = (
{
"hall_status" = "<null>";
hum = 111;
"light_status" = "<null>";
"node_id" = y2cfwecrw3hqznuxmfvf;
"node_name" = SVIN03;
"pir_status" = OFF;
"relay_status" = "<null>";
"smoke_status" = "<null>";
temp = 2132;
},
{
"node_name" = SVIN04;
nodeid = aj2w1aljw8nd65ax79dm;
},
{
"hall_status" = "<null>";
hum = 100;
"light_status" = "<null>";
"node_id" = mwmfl2og2l8888fjpj2d;
"node_name" = SVIN05;
"pir_status" = ON;
"relay_status" = "<null>";
"smoke_status" = "<null>";
temp = 45;
}
);
numberofnodeid = 3;
}
111
100
Could not cast value of type '__NSCFNumber' (0x10db6f878) to 'NSString' (0x10ca71568).
2018-10-11 08:11:05.352491+0700 IOT 2[1506:101847] Could not cast value of type '__NSCFNumber' (0x10db6f878) to 'NSString' (0x10ca71568).
error is in this line :
self.humArray.insert(Float(Int(nodeid as! String)!), at: 0)

Answer 1

First of all, you have to look at json_decode to read data from json in php
Example:
`$json = '{"foo-bar": 12345}';
$obj = json_decode($json);
print $obj->{'foo-bar'}; // this will print 12345`
How to get ON/OFF JSON value and store in Bool array ?
basically you have to add a new value to your onOff variable, something like
$onOff=array();
$val;
$obj = json_decode($json);
if (is_null($obj->{'name_of_the_alert'})) {
$val = 0
} else {
$val = $obj->{'name_of_the_alert'};
}
array_push($onOff,$obj->{'name_of_the_alert'});
How to get JSON value and store in Float array ?
Basically same thing, I haven't use PHP in a while, but just declare the array of the value type you need.
if JSON value is , how can i store value as 0 in XCODE ?
I guess you mean if it is null, in this case you have to do this
$onOff=array();
$val;
$obj = json_decode($json);
if (is_null($obj->{'name_of_the_alert'})) {
$val = 0
} else {
$val = $obj->{'name_of_the_alert'};
}
array_push($onOff,$obj->{'name_of_the_alert'});
Take into consideration that I may have some mistakes here because I am not familiar with newer PHP versions.
Good luck

Answer 2

From your question, it is clear that temp and hum are Number type(Int of Double). So use NSNumber rather than NSString as:
self.humArray.insert(Float(Int(nodeid as! NSNumber)!), at: 0)
As more swifty approach, you can update your code as:
if let nodeDict = node as? [String: Any] {
if let nodeid = nodeDict["node_id"] as? String {
self.nodeidArray.insert(nodeid, at: 0)
}
if let nodename = nodeDict["node_name"] as? String {
self.nodenameArray.insert(nodename, at: 0)
}
if let temp = nodeDict["temp"] as? Int {
self.tempArray.insert(Float(temp), at: 0)
}
if let hum = nodeDict["hum"] as? Int {
self.humArray.insert(Float(hum), at: 0)
}
}

Answer 3

There is plenty of issues with your code:
First, avoid using NSStuff in Swift3+ when there is the equivalent.
let request = NSMutableURLRequest(url: NSURL(string: http://talectric.com/wp-admin/a_p/iot/read_all.php")! as URL)
...
let task = URLSession.shared.dataTask(with: request as URLRequest) {
=>
let request = URLRequest(url: URL(string: http://talectric.com/wp-admin/a_p/iot/read_all.php")!)
...
let task = URLSession.shared.dataTask(with: request) {
See, you avoid already all the as URL, as URLRequest.
Avoid force unwrapping: Avoid using !.
Because if it's nil or with as! the cast fails (and then it's nil), you'll get a crash.
Use if let, guard let. Read this about Optional
As a sample, I would have wrote:
guard let url = URL(string:http...) else {
print("invalid URL")
return
}
let request = URLRequest(url: url)
Parsing part:
if let respondString = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? NSDictionary {
Get rid of NSDictionary, use [String: Any] instead, then get rid of .allowFragments, it's rarely useful (it makes sense on certains cases only) don't use the force unwrap on data!, and don't name your variable respondString
because that's clearly not a String and that's clearly misleading.
=>
guard let data = data else { return }
if let responseDict = try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
Now:
if let nodedata = respondString.value(forKey: "nodedata") as? NSArray {
for node in nodedata{
if let nodeDict = node as? NSDictionary {
if let nodeid = nodeDict.value(forKey: "node_id") {
self.nodeidArray.insert(nodeid as! String, at: 0)
}
if let nodeid = nodeDict.value(forKey: "node_name") {
self.nodenameArray.insert(nodeid as! String, at: 0)
}
if let nodeid = nodeDict.value(forKey: "temp") {
self.tempArray.insert(Float(nodeid as! String)!, at: 0)
}
if let nodeid = nodeDict.value(forKey: "hum") {
print(nodeid)
self.humArray.insert(Float(Int(nodeid as! String)!), at: 0)
}
}
}
}
No, no NSArray, no NSDictionary, avoid using value(forKey:) because it does what you think it does on a NSDictionary doing a object(forKey:), or simply subscript (using ["someKey"]) but on an Array you'll get an issue with an unexpected result I think.
Don't name all your var nodeid, it's harder to debug after ward, don't do a soft unwrap (if let) if just afterward you do a force unwrap on that value.
if let nodedata = responseDict["nodedata"] as? [[String: Any]] {
for aNode in nodedata {
if let id = aNode["node_id"] as? String {
self.nodeidArray.insert(nodeId, at: 0)
}
if let name = aNode["node_name"] as? String {
self.nodenameArray.insert(name, at: 0)
}
if let temp = aNode["temp"] as? String, let tempFloat = Float(temp) {
self.tempArray.insert(tempFloat, at: 0)
}
if let hum = aNode["hum"] as? String, let humFloat = Float(hum) {
self.humArray.insert(humFloat, at: 0)
}
}
}
That's much more readable.
Now instead of using insert(_:at:), it might be easier to use nodedata.inverted().
Now, let's talk about architecture:
What happens in your case, if you don't pass the if let hum = aNode["hum"] as? String, let humFloat = Float(hum) { on one iteration (let's say the second one which is exactly your case in the sample you gave there is no temp) but success on all the others?
Here what's going to happen:
self.nodeidArray[3] and self.humArray[3] won't be correct, they'll be desynchronized, right?
Because self.nodeidArray[2] should be with self.humArray[1].
Theses values are meant to be synce'd, so use a custom Struct/Class for it:
After all, Swift is a OOP (Object Oriented Programming) language, so use objects.
struct Node {
let id: String?
let name: String?
let humidity: Float?
let temperature: Float?
}
So instead of having:
var nodenameArray: [String] = []
var nodeidArray: [String] = []
var tempArray: [Float] = []
var humArray: [Float] = []
Just have:
var nodes: [Node] = []
And during the parsing, do
let node = Node.init(withDict: aNode)
nodes.append(node) //or insert it at 0
You can construct your own method init in Node, let's say:
func init(withDict dict: [String: Any]) {
if let id = dict["node_id"] as? String {
self.id = id
}
etc.
}
Having this Node class simplify. But using the JSONSerialization and init all the values manually could be avoided using Codable (available in Swift 4).
Side Note:
This code is not tested, there might be some glitch, typo etc. Let's focus on the explanation instead.
Lastly concerning the error:
Could not cast value of type '__NSCFNumber' (0x10db6f878) to
'NSString' (0x10ca71568). 2018-10-11 08:11:05.352491+0700 IOT
2[1506:101847] Could not cast value of type '__NSCFNumber'
(0x10db6f878) to 'NSString' (0x10ca71568).
error is in this line :
self.humArray.insert(Float(Int(nodeid as! String)!), at: 0)
The error means that at some point you tried to cas (using as) on a a (NS)String, but is was in fact NSNumber (in Swift, it's easily converted into an Int/Float, etc.), so it failed.
So the part that failed: nodeid as! String, because nodeid is not a (NS)String