I have a method here:
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
{
NSLog(#"PERIPHERAL: peripheralManager:%# didReceiveWriteRequests:%#", peripheral, requests);
NSString * result = [[requests valueForKey:#"description"] componentsJoinedByString:#""];
_label.text = result;
}
I receive the write request in an NSArray. Right now I am just converting the full array into a string and outputting the string into a text box. To make sure everything is set up correctly. It indeed is working, but I do not want the full array listed but just the value alone stored in a NSString.
I want this in a string:
Test
Not this:
CBATTRequest: 0x1702240 Central = , Characteristic = , Offset = 0, Value = test
This should be easy to accomplish and I am possibly just brain dead from a long day. How is this supposed to be done?
You need to consider that requests is an array of CBATTRequests, which have a value property containing an NSData object representing the data being written.
If you want one string representing all of the values, you need to iterate over requests and convert each of these NSData values to NSString and concatenate them. If I'm understanding your question correctly, this should be what you're looking for.
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests {
NSMutableString *output = [[NSMutableString alloc] init];
for (CBATTRequest *request in requests) {
NSString *stringValue = [[NSString alloc] initWithData:[request value] encoding:NSUTF8StringEncoding];
if (stringValue) {
[output appendString:stringValue];
}
}
_label.text = output.copy;
}
As a note, updating to Xcode 7 would help make this more clear, since the requests parameter of -peripheralManager:didReceiveWriteRequests: has updated to use Objective-C generics, and now has the type NSArray<CBATTRequest *> *.
Related
I have this is on the top of my program:
#property (strong, nonatomic) NSMutableData *data;
I thought this would allow me to store the value from every time this method runs:
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
{
for (CBATTRequest *request in requests) {
NSString *stringValue = [[NSString alloc] initWithData: [request value] encoding:NSUTF8StringEncoding];
// Have we got everything we need?
if ([stringValue isEqualToString:#"EOM"]) {
// We have, so show the data,
[self.textview setText:[[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding]];
}
// Otherwise, just add the data on to what we already have
[self.data appendData:[request value]];
}
}
This method waits for a write request to be received and stores the value in a string. I have a core bluetooth central that is sending three blocks of data. This is to get around the data transfer size restriction within bluetooth LE. The problem is I can't get the three values stored. I am trying to not just store the last value but add the new value to the end of a nsstring or nssdata every time the method is called. Any help would be greatly appreciated. I thought the property at the top would allow me to do it but it either only stores the last value or nothing at all. I am not used to the ways of objective c yet. Thanks.
Even this doesn't write anything to self.data:
NSString * result = [[requests valueForKey:#"value"] componentsJoinedByString:#""];
NSData* data = [result dataUsingEncoding:NSUTF8StringEncoding];
[self.data appendData:data];
// Log it
NSLog(#"%#",self.data);
You should use NSMutableArray instead of NSString as a mutable string.
- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
{
NSMutableString *stringValue = [[NSMutableString alloc] init];
for (CBATTRequest *request in requests) {
[stringValue appendString:[[NSString alloc] initWithData:[request value] encoding:NSUTF8StringEncoding]];
// Have we got everything we need?
if ([stringValue isEqualToString:#"EOM"]) {
// We have, so show the data,
[self.textview setText:[[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding]];
}
// Otherwise, just add the data on to what we already have
[self.data appendData:[request value]];
}
Remember kids when dealing with NSMutableData always initialize it!
_data = [[NSMutableData alloc] init];
This fixed the null problem for me.
- (void)retrieveData
{
NSURL * url = [NSURL URLWithString:#"***/connection.php"];
NSData * data = [NSData dataWithContentsOfURL:url];
_json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
_questionsArray = [[NSMutableArray alloc]init];
for (int i = 0; i < _json.count; i++)
{
NSString * qID = [[_json objectAtIndex:i] objectForKey:#"id"];
NSString * qTitle = [[_json objectAtIndex:i] objectForKey:#"question_title"];
NSString * qA = [[_json objectAtIndex:i] objectForKey:#"A"];
NSString * qB = [[_json objectAtIndex:i] objectForKey:#"B"];
NSString * qC = [[_json objectAtIndex:i] objectForKey:#"C"];
NSString * qD = [[_json objectAtIndex:i] objectForKey:#"D"];
NSString * qAnswer = [[_json objectAtIndex:i] objectForKey:#"question_answer"];
question * myQuestion = [[question alloc] initWithQuestionID:qID andQuestionName:qTitle andQuestionA:qA andQuestionB:qB andQuestionC:qC andQuestionD:qD andQuestionAnswer:qAnswer];
[_questionsArray addObject:myQuestion];
}
[_json enumerateObjectsUsingBlock:^(NSDictionary *questionDictionary, NSUInteger idx, BOOL *stop) {
//Here I'm treating the index like an NSNumber, if your code is expecting a string instead use
//#(idx).stringValue
[_questions setObject:questionDictionary forKey:#(idx)];
//or the modern equivalent
//questions[#(idx)] = questionDictionary;
//If you want to use your 'questions class' then create one and put it into the array instead of the dictionary pulled from the array.
}];
NSLog( #"%#", _questions );
}
Logs (null)
random gobledy gook so my post isn't mostly code
random gobledy gook so my post isn't mostly code
random gobledy gook so my post isn't mostly code
random gobledy gook so my post isn't mostly code
random gobledy gook so my post isn't mostly code
If I understand your question correctly it becomes something like this
self.questions = .... //I assume this is the array you reference 'question' objects that is created by your retrieve data method
//this used to be created by pulling an object out of your questions dictionary with the key i interpreted as a string.
//now that it's an array you should be able to just reference it by index, assuming they were inserted in order
//I'm also assuming that what comes out of the aray is a question object given the code you provided with the signature
//- (id) initWithQuestionID: (NSString *) qID andQuestionName: (NSString *) qName andQuestionA: (NSString *) qA andQuestionB: (NSString *) qB andQuestionC: (NSString *) qC andQuestionD: (NSString *) qD andQuestionAnswer: (NSString *) qAnswer
Question *nextQuestion = self.questions[i];
self.answer = nextQuestion.questionAnswer;
self.questionLabel.text = nextQuestion.questionLabel;
//and so on
I also suggest the following edit to replace your for loop. It uses a for in loop instead, this saves you from having to keep track of an index and looks cleaner. It also helps so you don't keep repeating the [_json objectAtIndex:i] chunk of code. I also use modern objective-c syntax to access the dictionary.
for (NSDictionary *questionDictionary in _json)
{
NSString * qID = questionDictionary[#"id"];
NSString * qTitle = questionDictionary[#"question_title"];
...
question * myQuestion = [[question alloc] initWithQuestionID:qID andQuestionName:qTitle andQuestionA:qA andQuestionB:qB andQuestionC:qC andQuestionD:qD andQuestionAnswer:qAnswer];
[_questionsArray addObject:myQuestion];
}
If you need the key along with the object in the dictionary then you can clean it up in a similar way with the enumerateObjectsUsingBlock
[_json enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
//your code here
}];
EDIT
It sounds like what your really wanting to do is to pull down your JSON but keep all your other code the way it was when you were using a dictionary that you got from your plist. So in this case you want your parsing function to return a dictionary instead of an array. If that's the case it's worth sidestepping into computer science for a second.
NSDictionarys are also known as a hash, map, symbol table, or associative array. Some languages (such as Lua) don't have an array collection like NSArray, they only have dictionaries. From a dictionary you can create many of the other collections your used to like arrays (and sets too). Heres how it works: Instead of an ordered collection of elements with an index, you place the items in a dictionary and use what would have been the index as the key, and the value becomes, well, the value. For example an array and it's equivalent associative array (aka dictionary):
NSArray *array = #[#"hello", #"world", #"!"];
NSDictionary *dictionary = #{#(1): #"hello",
#(2): #"world",
#(3): #"!"};
This is exactly what your doing when you load in the data from your plist because the first elements key is 0 followed by another dictionary, and I'm supposing that the next element in the list is 1 followed by another dictionary. Inside your parsing function it becomes
NSMutableDictionary *questions = [[NSMutableDictionary alloc] init];
[_json enumerateObjectsUsingBlock:^(NSDictionary *questionDictionary, NSUInteger idx, BOOL *stop) {
//Here I'm treating the index like an NSNumber, if your code is expecting a string instead use
//#(idx).stringValue
[questions setObject:questionDictionary forKey:#(idx)];
//or the modern equivalent
//questions[#(idx)] = questionDictionary;
//If you want to use your 'questions class' then create one and put it into the array instead of the dictionary pulled from the array.
}];
This of course assumes that your api is going to return the JSON questions in the order you want.
Okay I am new to objective C and am trying hard to learn it on my own with out bother the stacked overflow community to much but it is really quite different then what I'm used to (C++).
But I have come across a issue that I for the life of me can't figure out and I'm sure it's going be something stupid. But I am pulling questions and answers from a website that then will display on my iOS application by using this code.
NSString * GetUrl = [NSString stringWithFormat:#"http://www.mywebpage.com/page.php"];
NSString * GetAllHtml = [NSString stringWithContentsOfURL:[NSURL URLWithString:GetUrl] encoding:1 error:nil];
NSString *PullWholeQuestion = [[GetAllHtml componentsSeparatedByString:#"<tr>"] objectAtIndex:1];
NSString *FinishWholeQuestion = [[PullWholeQuestion componentsSeparatedByString:#"</tr>"] objectAtIndex:0];
After I get all of the webpage information I strip down each question and want to make it where it will do a loop process to pull the questions so basically I need to count how many array options there are for the FinishedWholeQuestion variable
I found this snippet online that seemed to work with there example but I cant repeat it
NSArray *stringArray = [NSArray arrayWithObjects:#"1", #"2", nil];
NSLog(#"count = %d", [stringArray count]);
"componentsSeparatedByString" returns an NSArray object, not a single NSString.
An array object can contain zero, one or more NSString objects, depending on the input.
If you change "FinishWholeQuestion" into a NSArray object, you'll likely get a few components (separate by a string).
And now that I'm looking at your code a little more closely, I see you're making an assumption that your array is always valid (and has more than 2 entries, as evidenced by the "objectAtIndex: 1" bit).
You should also change the first character of all your Objective-C variables. Best practices in Objective-C are that the first character of variables should always be lower case.
Like this:
NSString * getUrl = [NSString stringWithFormat:#"http://www.mywebpage.com/page.php"];
NSString * getAllHtml = [NSString stringWithContentsOfURL:[NSURL URLWithString:getUrl] encoding: NSUTF8StringEncoding error:nil];
NSArray * allQuestions = [getAllHtml componentsSeparatedByString:#"<tr>"];
if([allQuestions count] > 1)
{
// assuming there is at least two entries in this array
NSString * pullWholeQuestion = [allQuestions objectAtIndex: 1];
if(pullWholeQuestion)
{
NSString *finishWholeQuestion = [[pullWholeQuestion componentsSeparatedByString:#"</tr>"] objectAtIndex:0];
}
}
Currently, I have within my iPhone app a URL with which contains a JSON object that I must parse.
I am able to fetch the JSON object, convert the object to an NSString, now the issue is parsing the object/NSString object.
I am currently using SBJSON.
How do I go about iterating through the key elements of the JSON object using SBJSON's framework?
{
"status":"SUCCESS",
"fields":[
{
"type":"instant",
"field":"GenerationPower",
"label":"now",
The JSON object is MUCH larger than just these keys and key elements but once this issue is resolved, I'm sure the rest of the JSON object will be easy since i'll have a reference.
Thank you Stackoverflow!
EDIT:
Here's some code to clarify my issue.
+ (NSString *) pullingInfo
{
NSURL *solarWebURL = [NSURL URLWithString:myurl];
if (solarWebURL)
{
NSLog(#"Calling: %#", solarWebURL);
NSData *jsonData = [NSData dataWithContentsOfURL:solarWebURL];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
return jsonString;
}
NSString* errorMessage = #"Error reading URL";
return errorMessage;
}
+ (NSDictionary *) jsonDictionaryObject
{
NSDictionary * jsonDictionary = [[NSDictionary alloc] init];
NSString * monroeString = [MonroeParser pullingInfo];
return jsonDictionary;
}
So as I said before, I have already loaded the JSON object into an NSString object "jsonString". Now I would like to start parsing the string.
I figure I may not even need to use JSON's framework for parsing, I can probably just parse the NSString using NSString conventions provided by Apple.
Any idea's? But maybe this isn't efficient....
Sine you are using SBJSON, why are you even converting the NSData to an NSString? You can use -objectWithData method for SBJSONParser to directly read the NSData into an NSDictionary.
http://sbjson.org/api/3.2/Classes/SBJsonParser.html#//api/name/objectWithData:
Let pullingInfo return an id. And in you calling function check if the id is of type NSDictionary or NSArray and parse accordingly.
When I scan the barcode and I get some value if it is Equal=2 then I need to display with == and if it is Equal=3 then I need to display with = and if the value is 4 then invalid.
But Scanned Barcode are of integer value -- when decode using NSASCII it is displaying only till value 127 after that it is showing invalid results. Eg: if my Barcode value = 9699 the result value=jem then my added result value=jem= actualstring value=%åasc value id only showing 37
Here is my code:
- (void) readerView:(ZBarReaderView *)view didReadSymbols:(ZBarSymbolSet *)syms fromImage:(UIImage *)img
{
// do something useful with results -- cool thing is that you get access to the image too
for (ZBarSymbol *symbol in syms) {
[resultsBox setText:symbol.data];
if ([resultsBox.text length] == 2) {
addedresult.text = [resultsBox.text stringByAppendingString:#"=="];
} else if ([resultsBox.text length] == 3) {
addedresult.text = [resultsBox.text stringByAppendingString:#"="];
} if ([resultsBox.text length] >= 4) {
addedresult.text = #"Invalid";
}
[Base64 initialize];
NSString *myString = [[NSString alloc]initWithString:addedresult.text];
NSData * data = [Base64 decode:myString];
NSString * actualString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"%#",actualString);
labeltext.text= actualString;
int asc = [actualString characterAtIndex:0];
label.text = [NSString stringWithFormat:#"%d", asc];
[actualString release];
break;
}
}
Since someone revived this question's comments, i'll revive this entire post.
You shouldn't go through NSData to create an NSString from something you already have, and you're probably losing something along the way. Go directly to NSString using stringWithFormat. Also, ASCII will come back and byte you later, if you have a choice, use UTF8.
NSString *actualStringUTF8 = [NSString stringWithFormat:#"%#",[addedresult.text urlEncodeUsingEncoding:NSUTF8StringEncoding]];
NSString *actualStringASCII = [NSString stringWithFormat:#"%#",[addedresult.text urlEncodeUsingEncoding:NSUTF8StringEncoding]];
NSLog(#"%#",actualStringUTF8);
NSLog(#"%c",[actualStringUTF8 UTF8String]); //This is a const char*
Secondly, I looked into the SDK and it says symbol.data is already an NSString*. Depending on what you want, you may not need to do anything. If you do end up needing to change encoding, make sure you understand why you need to (one good reason is "the rest of the application uses NS****StringEncoding").
Also make sure you compare strings the correct "Objective-C" way:
[actualString isEqualToString: testString];
NOT actualString == testString;