My callbacks aren't being called. I'm not that familiar with dispatch_async so any thoughts? Point being, I never see a Response.
+ (void)asyncRequest:(NSURLRequest *)request
success:(void(^)(NSData *, NSURLResponse *))successBlock_
failure:(void(^)(NSData *, NSError *))failureBlock_
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSURLResponse *response = nil;
NSError *error = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request
returningResponse:&response
error:&error];
NSString *result = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"-----------------result %#", result);
if (error) {
failureBlock_(data,error);
} else {
successBlock_(data,response);
}
[pool release];
});
}
Why are you implementing your own sendAsync method?
You should look into using the provided one instead, NSURLClassReference
EDIT
Assuming you're developing for OSX, not iOS. Evidently this method is not available for iOS.
Related
About every single tutorial and example on the internet I see shows how to fetch JSON from some url and show it in Tableview. This is not my problem I know how to do that with AFNetworking framework or with native APIs.
My problem is that after I have downloaded the JSON, I want to show some of it in my UIView labels. I have actually succeeded doing this when I was trying to find a way around NSURLSession inability to cache in iOS 8. But I didn't realize that it was synchronous.
Factory.m
+ (Factory *)responseJson
{
static Factory *shared = nil;
shared = [[Factory alloc] init];
NSHTTPURLResponse *response = nil;
NSString *jsonUrlString = [NSString stringWithFormat:#"http://urltojson.com/file.json"];
NSURL *url = [NSURL URLWithString:[jsonUrlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSError *error = nil;
NSURLRequest *request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestReturnCacheDataElseLoad
timeoutInterval:10.0];
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
if (error) {
NSLog(#"error");
} else {
//-- JSON Parsing
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:nil];
//NSLog(#"Result = %#",result);
shared.responseJson = result;
}
return shared;
}
My question is that is it possible to use for example AFNetwoking to do the same thing? Am I missing some method that I need to call like in case of a TableView
[self.tableView reloadData];
I would like to use that framework because I need to check Reachability and it seems to implement it already.
Edit as asked to show more code
ViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
[self factoryLoad];
[self setupView];
}
- (void)factoryLoad
{
Factory *shared = [Factory responseJson];
self.titles = [shared.responseJson valueForKeyPath:#"data.title"];
dispatch_async(dispatch_get_main_queue(), ^{
[self.collectionView reloadData];
});
}
- (void)setupView
{
self.issueTitleLabel.text = [self.titles objectAtIndex:0];
}
There are a couple oddities in the code you posted.
Factory, which appears to be a singleton class, should be instantiated inside a dispatch_once to ensure thread safety.
In ViewController.m, you are calling factoryLoad on the main thread, which is subsequently calling sendSynchronousRequest on the main thread. Apple's NSURLConnection Documentation warns against calling this function on the main thread as it blocks the thread, making your application unresponsive to user input.
You should not be passing in nil as the error parameter in NSJSONSerialization JSONObjectWithData:.
In your case I would recommend separating the fetching of data from the construction of your singleton object.
Factory.m
+(Factory *)sharedFactory {
static Factory *sharedFactory = nil;
dispatch_once_t onceToken;
dispatch_once(&onceToken, {
sharedFactory = [[Factory alloc] init];
});
}
-(void)fetchDataInBackgroundWithCompletionHandler:(void(^)(NSURLResponse *response,
NSData *data,
NSError *error)
completion {
NSHTTPURLResponse *response = nil;
NSString *jsonUrlString = [NSString stringWithFormat:#"http://urltojson.com/file.json"];
NSURL *url = [NSURL URLWithString:[jsonUrlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSURLRequest *request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestReturnCacheDataElseLoad
timeoutInterval:10.0];
NSOperationQueue *downloadQueue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:request
queue:downloadQueue
completionHandler:completion];
}
Now you should be able to create a reference to the data with a guarantee that the download request has finished and thus the data will exist.
ViewController.m
-(void)factoryLoad {
[[Factory sharedFactory] fetchDataInBackgroundWithCompletionHandler:^(void)(NSURLResponse *response, NSData *data, NSError *error){
if(!error) {
NSError *error2;
NSDictionary *serializedData = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error2];
if(error2){ /* handle error */ }
self.titles = [serializedData valueForKeyPath:#"data.title"];
[Factory sharedFactory].responseJSON = serializedData;
}
else {
// handle error
}
}];
}
This will guarantee that the download has completed before you try to access any of the downloaded information. However, I've left a few things out here, including any sort of activity indicator displaying to the user that the app is doing something important in the background. The rest is, uh, left as an exercise to the reader.
Ok I took a deeper investigation into Morgan Chen's answer and how to block.
The example code took some modification but I think It works as it should and is better code.
In Factory.m
+ (Factory *) sharedInstance
{
static Factory *_sharedInstance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedInstance = [[self alloc] init];
});
return _sharedInstance;
}
-(void)fetchDataInBackgroundWithCompletionHandler: (void(^)(BOOL success, NSDictionary *data, NSError *error)) block
{
NSString * baseURL = #"http://jsonurl.com/file.json";
AFHTTPRequestOperationManager * manager = [[AFHTTPRequestOperationManager alloc] init];
__weak AFHTTPRequestOperationManager *weakManager = manager;
NSOperationQueue *operationQueue = manager.operationQueue;
[manager.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
switch (status) {
case AFNetworkReachabilityStatusReachableViaWWAN:
case AFNetworkReachabilityStatusReachableViaWiFi:
NSLog(#"internet!");
[weakManager.requestSerializer setCachePolicy:NSURLRequestReloadIgnoringCacheData];
[operationQueue setSuspended:NO];
break;
case AFNetworkReachabilityStatusNotReachable:
NSLog(#"no internet");
[weakManager.requestSerializer setCachePolicy:NSURLRequestReturnCacheDataElseLoad];
[operationQueue setSuspended:YES];
break;
default:
break;
}
}];
[manager.reachabilityManager startMonitoring];
manager.responseSerializer = [AFJSONResponseSerializer serializer];
[manager GET:baseURL parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
if (responseObject && [responseObject isKindOfClass:[NSDictionary class]]) {
block(YES, responseObject, nil);
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) { // invalid request.
NSLog(#"%#", error.localizedDescription);
block(NO, nil, error);
}];
}
In ViewController.m I call this method on viewDidLoad
-(void)factoryLoad
{
[[Factory sharedInstance] fetchDataInBackgroundWithCompletionHandler:^(BOOL success, NSDictionary *data, NSError *error) {
if (success) {
NSLog(#"we have stuff");
self.responseData = data;
self.titles = [self.responseData valueForKeyPath:#"data.title"];
[self setupView];
dispatch_async(dispatch_get_main_queue(), ^{
[self.collectionView reloadData];
});
}
}];
}
I have two methods and I need to use a variable from first as input parameter in the second. How can I do it? My code is :
First method
-(NSString*)getResponseData :(NSString*) apiHttp {
NSString *code = #"&code=";
NSString *finalLink = [[NSString alloc] initWithFormat:#"%#%#",apiHttp,phoneNumber];
NSURLRequest *request = [NSURLRequest requestWithURL:
[NSURL URLWithString:finalLink]];
NSLog(#"%#", finalLink);
__block NSDictionary *json;
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
json = [NSJSONSerialization JSONObjectWithData:data
options:0
error:nil];
NSLog(#"Async JSON: %#", json);
NSError *error;
NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
myString = [jsonDict objectForKey:#"result"];
// NSLog(#"%#", myString);
}];
return myString;
}
Second method:
-(void)showCodeView:(NSString*) ifString{
if([ifString isEqualToString:#"200"]){
aPasswordField.hidden = NO;
[aPasswordField setBorderStyle:UITextBorderStyleLine];
aPasswordField.layer.cornerRadius=1.0f;
aPasswordField.layer.masksToBounds=YES;
aPasswordField.layer.borderColor=[[UIColor whiteColor]CGColor];
aPasswordField.layer.borderWidth= 0.8f;
UIColor *color = [UIColor lightTextColor];
aPasswordField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:#"Код" attributes:#{NSForegroundColorAttributeName: color}];
self.aPasswordField.delegate = self;
}
}
And this is how I call them:
[self getResponseData:apiHttp];
[self showCodeView:myString];
So I can't understand why my myString is null after [self getResponseData:apiHttp]; was called even if my method retutns it.
You are calling two methods after another but are missing that the first one is asynchronous.
When you call sendAsynchronousRequest:queue:completionHandler: it will perform the request asynchronously (not waiting) and call the completion block once it has a response. Since the code doesn't wait for this to happen, getResponseData: immediately returns the current value of myString which is nil if it's not set yet.
You can see how this is working by adding a some log statements before and after each method call:
NSLog(#"Before getResponseData:");
[self getResponseData:apiHttp];
NSLog(#"After getResponseData:");
NSLog(#"Before showCodeView:");
[self showCodeView:myString];
NSLog(#"After showCodeView:");
and the same for the asynchronous request
NSLog(#"Before sendAsynchronousRequest:");
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data,
NSError *connectionError) {
NSLog(#"After sendAsynchronousRequest:");
// the rest of the completion block ...
There are many ways to deal with this. One would be to add a block argument for the getResponseData: method that is called from the completion handler of the request.
If you are unused to working with blocks, a simpler but more tightly coupled alternative is to call [self showCodeView:myString]; from inside of the completion handler.
You want to perform showCodeView only when your asynchronous getResponseData finishes, so implement your own rendition of the completion block pattern:
- (void)getResponseData :(NSString*) apiHttp completionHandler:(void (^)(NSDictionary *, NSError *))completion {
NSString *code = #"&code=";
NSString *finalLink = [[NSString alloc] initWithFormat:#"%#%#",apiHttp,phoneNumber];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:finalLink]];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
if (completion) {
if (connectionError) {
completion(nil, connectionError);
} else {
NSError *parseError;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&parseError];
completion(json, parseError);
}
}
}];
}
Note, I've eliminated that __block variable and changed the return type to void (since this doesn't return anything ... the value is passed back via the completion block).
You can then do:
[self getResponseData:apiHttp completionHandler:^(NSDictionary *json, NSError *error) {
if (error) {
// handle this however appropriate for your app
} else {
NSString *myString = json[#"result"];
[self showCodeView:myString];
}
}];
I am really new to Objective-C.
First please see the code:
Here it is the property:
#property (atomic) IBOutlet NSTextView *txtResponse;
And here it is the action:
- (IBAction)sendReq:(id)sender {
#synchronized(self)
{
request *req = [[request alloc] init];
voidCallback callback = ^(NSURLResponse *resp, NSData *data, NSError *error) {
NSString *val = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
[self.txtResponse setString:val];
//NSLog(val);
};
[req setUrl:[[NSURL alloc] initWithString:#"http://foo.bar"]];
[req setCallback:callback];
[req send];
}
}
The UI freezes when I try to use [self.txtResponse setString:val];
I also tried the code without #synchronized(self)
Where is the problem?
Thanks in advance!
3rd day that I am working with objective-c and finally found the answer :)
I used the performSelectorOnMainThread and solved the problem
- (IBAction)sendReq:(id)sender {
request *req = [[request alloc] init];
voidCallback callback = ^(NSURLResponse *resp, NSData *data, NSError *error) {
NSString *val = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
[self performSelectorOnMainThread:#selector(setResponseValue:) withObject:val waitUntilDone:NO];
};
[req setUrl:[[NSURL alloc] initWithString:#"http://programming.com"]];
[req setCallback:callback];
[req send];
}
- (void)setResponseValue:(NSString *)resp
{
[self.txtResponse setString:resp];
//NSLog(resp);
}
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My Code for NSURLConnection with sendSynchronousRequest works fine but how can i change it to an async request? i tried a lot but nothing would work.
if the Request is empty i´ll get an empty Array with [[]] .
How can i catch it for an Alert Message?
Please help ...
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSString *urlString = #"http://www.xyz.at/sample.php";
NSURL *url = [NSURL URLWithString:urlString];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:url];
[request setHTTPMethod:#"POST"];
NSMutableData *body = [NSMutableData data];
NSString *postWerte = [NSString stringWithFormat:#"id=%#", self.textfeld.text];
[body appendData:[postWerte dataUsingEncoding:NSUTF8StringEncoding]];
[request setHTTPBody:body];
NSError *error = nil;
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&error];
NSLog(#"Error: %#", error.description);
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
const char *convert = [returnString UTF8String];
NSString *responseString = [NSString stringWithUTF8String:convert];
NSMutableArray *meinErgebnis = [responseString JSONValue];
NSString *cycle = #"";
NSString *kopfdaten = [NSString stringWithFormat:#"Sendungsart: %#\r\nGewicht: %# kg\r\n\r\n", [[meinErgebnis objectAtIndex:0] objectForKey:#"ParcelTypeDescription"], [[meinErgebnis objectAtIndex:0] objectForKey:#"Weight"]];
cycle = [cycle stringByAppendingString:kopfdaten];
for(int i = 1; i < meinErgebnis.count; i++)
{
NSString *myValue = [NSString stringWithFormat:#"%# PLZ: %#\r\nStatus: %#\r\n\r\n",
[[meinErgebnis objectAtIndex:i] objectForKey:#"EventTimestamp"],
[[meinErgebnis objectAtIndex:i] objectForKey:#"EventPostalCode"],
[[meinErgebnis objectAtIndex:i] objectForKey:#"ParcelEventReasonDescription"]];
cycle = [cycle stringByAppendingString:myValue];
}
self.ergebnis.text = [NSString stringWithFormat:#"%#", cycle];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
[self.textfeld resignFirstResponder];
You could:
create an NSOperationQueue, and
call sendAsynchronousRequest, placing all of your NSData processing code inside the completion block.
Thus, instead of:
NSURLResponse *response = nil;
NSError *error = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
// now process resulting `data`
Use:
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
// now process resulting `data`
}];
Alternatively, you could implement the NSURLConnectionDataDelegate methods. For more information on that, see the Using NSURLConnection section of the URL Loading System Programming Guide.
You say "if the request is empty": I assume you mean "if the data returned is empty". And you say it is [[]]. If that's really what you're getting, it sounds like an array with one item (which itself, is an empty array). Or is it [] (which is an empty array)? Or is it nil?
I'm going to assume that the data returned was [], an empty array.
I'd also suggest you consider using NSJSONSerialization, the built in JSON parser, but obviously you can use JSONValue if you really want.
Finally, your implementation is skipping the first entry (NSArray uses a zero-based index). I'm assuming that was unintentional.
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
if (error) {
NSLog(#"%s: sendAsynchronousRequest error: %#", __FUNCTION__, error);
return;
}
NSError *parseError;
NSArray *meinErgebnis = [NSJSONSerialization JSONObjectWithData:data options:0 error:&parseError];
if (parseError) {
NSLog(#"%s: JSONObjectWithData error: %#", __FUNCTION__, parseError);
return;
}
if ([meinErgebnis count] == 0) {
NSLog(#"%s: meinErgebnis empty", __FUNCTION__);
return;
}
for (NSDictionary *dictionary in meinErgebnis)
{
// now process each dictionary entry in meinErgebnis
}
// etc.
}];
I attempted to make -[NSString stringWithContentsOfURL:encoding:error:] asynchronous, by running it a-synchronically from a background thread:
__block NSString *result;
dispatch_queue_t currentQueue = dispatch_get_current_queue();
void (^doneBlock)(void) = ^{
printf("done! %s",[result UTF8String]);
};
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
(unsigned long)NULL), ^(void) {
result = [NSString stringWithContentsOfURL:[NSURL URLWithString:#"http://www.google.com/"] encoding:NSUTF8StringEncoding error:nil];
dispatch_sync(currentQueue, ^{
doneBlock();
});
});
Its working fine, and most importantly, its asynchronous.
My question is if it's safe to do this, or could there be any threading problems etc.?
Thanks in advance :)
That should be safe, but why reinvent the wheel?
NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:#"http://www.google.com"]];
[NSURLConnection sendAsynchronousRequest:req queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
// etc
}];
You can also use:
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
NSError *error = nil;
NSString *searchResultString = [NSString stringWithContentsOfURL:[NSURL URLWithString:searchURL]
encoding:NSUTF8StringEncoding
error:&error];
if (error != nil) {
completionBlock(term,nil,error);
}
else
{
// Parse the JSON Response
NSData *jsonData = [searchResultString dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *searchResultsDict = [NSJSONSerialization JSONObjectWithData:jsonData
options:kNilOptions
error:&error];
if(error != nil)
{
completionBlock(term,nil,error);
}
else
{
//Other Work here
}
}
});
But yes, it should be safe. I've been told though to use NSURLConnection instead due to error calls and such when communicating via the internet. I'm still doing research into this.
-(void)loadappdetails:(NSString*)appid {
NSString* searchurl = [#"https://itunes.apple.com/lookup?id=" stringByAppendingString:appid];
[self performSelectorInBackground:#selector(asyncload:) withObject:searchurl];
}
-(void)asyncload:(NSString*)searchurl {
NSURL* url = [NSURL URLWithString:searchurl];
NSError* error = nil;
NSString* str = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&error];
if (error != nil) {
NSLog(#"Error: %#", error);
}
NSLog(#"str: %#", str);
}