I am a new bee to iphone programming and I need some help with printing.
I have a view with UIScrollView,UITextView and UIImage as its subviews. I would like to print this view such that the complete content of the scroll view and text view will available be available on the printed page. I went through the UIPrintFormatter but I am not sure of how to use it for my requirement. It would be really great if someone could give me a good answer(example\sample code) for my problem.
Thanks a lot in advance!
Came randomly to this question. No answer yet! Little help from code,
- (void) didPressPrintExpenseButton {
void (^completionHandler)(UIPrintInteractionController *, BOOL, NSError *) =
^(UIPrintInteractionController *pic, BOOL completed, NSError *error) {
if (!completed && error) NSLog(#"Print error: %#", error);
};
NSData *pdfData = [self generatePDFDataForPrinting];
printController.printingItem = pdfData;
[printController presentAnimated:YES completionHandler:completionHandler];
}
Related
How to get score of local player from Leaderboard Game Center? I tried this code, but it returns nothing. Anybody know how to solve it, or is there better way how to get score?
- (NSString*) getScore: (NSString*) leaderboardID
{
__block NSString *score;
GKLeaderboard *leaderboardRequest = [[GKLeaderboard alloc] init];
if (leaderboardRequest != nil)
{
leaderboardRequest.identifier = leaderboardID;
[leaderboardRequest loadScoresWithCompletionHandler: ^(NSArray *scores, NSError *error) {
if (error != nil)
{
NSLog(#"%#", [error localizedDescription]);
}
if (scores != nil)
{
int64_t scoreInt = leaderboardRequest.localPlayerScore.value;
score = [NSString stringWithFormat:#"%lld", scoreInt];
}
}];
}
return score;
}
I think, that method have to wait for completion of [leaderboardRequest loadScoresWithCompletionHandler: ...
Is it possible?
Your code appears to not have any bugs that I can see. I would recommend displaying the standard leaderboard interface to see if your code that reports the scores is actually working correctly. If so, you should see the scores in the leaderboard. The code below works in my game, and I know the score reporting is working properly because it shows in the default game center UI.
GKLeaderboard *leaderboardRequest = [[GKLeaderboard alloc] init];
leaderboardRequest.identifier = kLeaderboardCoinsEarnedID;
[leaderboardRequest loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
if (error) {
NSLog(#"%#", error);
} else if (scores) {
GKScore *localPlayerScore = leaderboardRequest.localPlayerScore;
CCLOG(#"Local player's score: %lld", localPlayerScore.value);
}
}];
If you aren't sure how, the code below should work to show the default leaderboard (iOS7):
GKGameCenterViewController *gameCenterVC = [[GKGameCenterViewController alloc] init];
gameCenterVC.viewState = GKGameCenterViewControllerStateLeaderboards;
gameCenterVC.gameCenterDelegate = self;
[self presentViewController:gameCenterVC animated:YES completion:^{
// Code
}];
You cannot return score outside the block. In this code first "return score" will be executed before the method "loadScoresWithCompletionHandler". Additionally you haven't set initial value for "score", this method will return completely random value.
I suggest you to put your appropriate code inside the block, instead of:
int64_t scoreInt = leaderboardRequest.localPlayerScore.value;
score = [NSString stringWithFormat:#"%lld", scoreInt];
The leaderboard request completes after the return of your method. This means that you are returning a null string.
The method you put the leaderboard request in should be purely for sending the request. The method will be finished executing before the leaderboard request is complete thus your "score = [NSString stringWithFormat:#"%lld", scoreInt];" line is being executed AFTER the return of the "score" which is null until that line is executed.
The solution is to not return the outcome of the completion handler using the method that sends the request. The score is definitely being retrieved correctly, so just do whatever you need to with the score inside of the completion handler. You have no way to know when the completion handler is going to be executed. This, in fact, is the reason why Apple allows you to store the code to be executed in a block! Although, it can be confusing to understand how to work with blocks that will definitely be executed later, or in your situation, sometime after the method is returning.
The best way to handle your situation is to not return anything in this method and just use the "score" variable as you intend to after the block has set score to a non-null value!
I am using GoogleDrive API in my application to upload files from my application. So far I succeeded and finding good results for uploading all types of files.
I followed Google example to upload files.
I am trying to show the progress, dependent on file size, while uploading. I have gone through many classes in the google given example code but there isn't much result.
Steps followed to get the file uploading progress :
I have found below method In GTLServices.m
- (void)setUploadProgressBlock:(GTLServiceUploadProgressBlock)block {
[uploadProgressBlock_ autorelease];
uploadProgressBlock_ = [block copy];
if (uploadProgressBlock_) {
// As above, we need the fetcher to call us back when bytes are sent.
SEL sentDataSel = #selector(objectFetcher:didSendBytes:totalBytesSent:totalBytesExpectedToSend:);
[[self objectFetcher] setSentDataSelector:sentDataSel];
}
}
After that in MyViewController.m written like this
[self.driveService setUploadProgressBlock:^(GTLServiceTicket *ticket, unsigned long long numberOfBytesRead, unsigned long long dataLength) {
NSLog(#"uploading");
}];
Above NSLog never getting excused because of this I am unable to get uploaded data bytes. By debugging I come across as uploadProgressBlock_ always showing nil. may be this resone my block handler not getting executed.
Please suggest me if I did any mistake to work it out.
If any one have idea to get the bytes of data uploaded to google drive for a file please suggest me. Your suggestions are more useful to my work.
Thanks in advance.
Consolidated Answer by taking our folks suggestions:
Here is the code to get upload progress information
GTLServiceTicket *uploadTicket= [self.driveService executeQuery:query completionHandler:^(GTLServiceTicket *ticket,GTLDriveFile *updatedFile,NSError *error)
{
if (error == nil)
{
[self.delegate completedFileUploadingToGoogleDrive];
NSError *fileDeletionError=nil;
[[NSFileManager defaultManager] removeItemAtPath:absalutePath error:&fileDeletionError];
} else
{
[self.delegate errorOccoredWhileUploadingToGoogleDrive:error];
}
}];
[uploadTicket setUploadProgressBlock:^(GTLServiceTicket *ticket, unsigned long long totalBytesWritten, unsigned long long totalBytesExpectedToWrite) {
[self.delegate uploadedFileInfoInKB:(float)totalBytesExpectedToWrite/1024 and:(float)totalBytesWritten/1024];
}];
Happy Coding!!
I have succeeded in using the upload block callback... assign it to the GTLServiceTicket object you obtain from the executeQuery method.
Sample:
GTLServiceTicket *uploadTicket = [self.driveService executeQuery:query completionHandler:^(GTLServiceTicket *ticket, GTLDriveFile *insertedFile, NSError *error)
{ // completion
}];
[uploadTicket setUploadProgressBlock:^(GTLServiceTicket *ticket, unsigned long long totalBytesWritten, unsigned long long totalBytesExpectedToWrite)
{
// progress
}
I recently used FabioL's answer but in Swift 2.3, it looks like this
let serviceTicket = service.executeQuery(query, completionHandler: { (ticket, insertedFile , error) -> Void in
let myFile = insertedFile as? GTLDriveFile
if error == nil {
alert.title = "Image Uploaded"
alert.message = "100%"
if progressView != nil {
progressView!.progress = 1
}
} else {
print("An Error Occurred! \(error)")
alert.title = "There was an error uploading"
}
})
//update UI on progress
serviceTicket.uploadProgressBlock = {(ticket, written, total) in
if progressView != nil {
let progressCalc: Float = (Float(written)/Float(total))
alert.message = "\(progressCalc*100)%"
progressView!.progress = progressCalc
}
}
As the upload happens it updates a ProgressView and on completion it changes the title and message of an UIAlertViewController
I suspect it may have to do with the lack of the NS_BLOCKS_AVAILABLE #define having been set in your project. If so, then instead of using -setUploadProgressBlock:, I think you need to define a method like:
- (void)ticket:(GTLServiceTicket *)ticket
hasDeliveredByteCount:(unsigned long long)numberOfBytesRead
ofTotalByteCount:(unsigned long long)dataLength;
And then specify it as the callback to use in your code, like:
[self.driveService setUploadProgressSelector:#selector(ticket:hasDeliveredByteCount:ofTotalByteCount:)];
(Search for uploadProgressSelector in GTLService.h; there's a comment there that may be helpful.)
Part of my app has a photo browser, somewhat similar to Apple's Photos app, with an initial view controller to browse photo thumbnails and a detail view that's shown when you tap on a photo.
I'm using ALAssetsLibrary to access photos, and I pass an array of ALAsset URL's to my detail view controller so you can swipe from one photo to the next.
Everything works great, until I receive an ALAssetsLibraryChangedNotification while swiping from one photo to another (in the detail view controller), which often results in a crash:
NOTIFICATION: the asset library changed // my own NSLog for when the
notification occurs
loading assets... // my own NSLog for when I start reloading assets in
the thumbnail browser
Assertion failed: (size == bytesRead), function
-[ALAssetRepresentation _imageData], file /SourceCache/AssetsLibrary/MobileSlideShow-1373.58.1/Sources/ALAssetRepresentation.m,
line 224.
The specific line of code it crashes on, is in calling [currentRep metadata] as shown here:
- (void)someMethod {
NSURL *assetURL = [self.assetURLsArray objectAtIndex:index];
ALAsset *currentAsset;
[self.assetsLibrary assetForURL:assetURL resultBlock:^(ALAsset *asset) {
[self performSelectorInBackground:#selector(configureDetailViewForAsset:) withObject:asset];
} failureBlock:^(NSError *error) {
NSLog(#"failed to retrieve asset: %#", error);
}];
}
- (void)configureDetailViewForAsset:(ALAsset *)currentAsset {
ALAssetRepresentation *currentRep = [currentAsset defaultRepresentation];
if (currentAsset != nil) {
// do some stuff
}
else {
NSLog(#"ERROR: currentAsset is nil");
}
NSDictionary *metaDictionary;
if (currentRep != nil) {
metaDictionary = [currentRep metadata];
// do some other stuff
}
else {
NSLog(#"ERROR: currentRep is nil");
}
}
I understand that once a notification is received, it invalidates any references to ALAsset and ALAssetRepresentation objects... but how am I supposed to deal with the situation where it invalidates something right in the middle of trying to access it?
I've tried setting a BOOL, right when receiving the notification to completely abort and prevent [currentRep metadata] from ever being called, but even that doesn't catch it every time:
if (self.receivedLibraryChangeNotification) {
NSLog(#"received library change notification, need to abort");
}
else {
metaDictionary = [currentRep metadata];
}
Is there anything I can do? At this point I'm almost ready to give up on using the ALAssetsLibrary framework.
(note this unresolved thread on the Apple dev forums describing the same issue: https://devforums.apple.com/message/604430 )
It seems the problem is around here:
[self.assetsLibrary assetForURL:nextURL
resultBlock:^(ALAsset *asset) {
// You should do some stuff with asset at this scope
ALAssetRepresentation *currentRep = [asset defaultRepresentation];
// Assume we have a property for that
self.assetRepresentationMetadata = [currentRep metadata];
...
// assume we have a method for that
[self updateAssetDetailsView];
}
failureBlock:^(NSError *error) {
NSLog(#"failed to retrieve asset: %#", error);
}];
Once you have got user asset it is better to copy asset information by providing necessary data to your details controller subviews or by caching for later use. It can be helpful for avoiding ALAsset invalidation troubles. When notification ALAssetsLibraryChangedNotification sent you may need to discard details controller and query the Library content from the beginning.
I have an App which stores images to Custom Library in Photo Album in iphone.
I called the following Function of ALAssetLibrary
-(void)saveImage:(UIImage*)image toAlbum:(NSString*)albumName withCompletionBlock:(SaveImageCompletion)completionBlock
{
//write the image data to the assets library (camera roll)
[self writeImageToSavedPhotosAlbum:image.CGImage orientation:(ALAssetOrientation)image.imageOrientation
completionBlock:^(NSURL* assetURL, NSError* error) {
//error handling
if (error!=nil) {
completionBlock(error);
return;
}
//add the asset to the custom photo album
[self addAssetURL: assetURL
toAlbum:albumName
withCompletionBlock:completionBlock];
}];
}
in my SaveImage IBAction
-(IBAction)saveToLib:(id)sender
{
UIImage *savedImage = imgPicture.image;
NSLog(#"Saved Image%#",savedImage);
[self.library saveImage:savedImage toAlbum:#"Touch Code" withCompletionBlock:^(NSError *error) {
if (error!=nil) {
NSLog(#"Big error: %#", [error description]);
}
}];
}
but my application keep getting Crashed
Help me out
Thanks in Advance
It seems that you are not calling the [self.library saveImage:savedImage toAlbum:#....] correctly. If you are following this web site, add #import "ALAssetsLibrary+CustomPhotoAlbum.h" in your view controller.
Not sure if it is the problem. Sorry if this workaround is the wrong approach.
Problem is the file from the website he downloaded.
I had the same issue and rewriting the code myself solved this.
Maybe encoding or something like this...
I am working on catching errors in my app, and I am looking into using NSError. I am slightly confused about how to use it, and how to populate it.
Could someone provide an example on how I populate then use NSError?
Well, what I usually do is have my methods that could error-out at runtime take a reference to a NSError pointer. If something does indeed go wrong in that method, I can populate the NSError reference with error data and return nil from the method.
Example:
- (id) endWorldHunger:(id)largeAmountsOfMonies error:(NSError**)error {
// begin feeding the world's children...
// it's all going well until....
if (ohNoImOutOfMonies) {
// sad, we can't solve world hunger, but we can let people know what went wrong!
// init dictionary to be used to populate error object
NSMutableDictionary* details = [NSMutableDictionary dictionary];
[details setValue:#"ran out of money" forKey:NSLocalizedDescriptionKey];
// populate the error object with the details
*error = [NSError errorWithDomain:#"world" code:200 userInfo:details];
// we couldn't feed the world's children...return nil..sniffle...sniffle
return nil;
}
// wohoo! We fed the world's children. The world is now in lots of debt. But who cares?
return YES;
}
We can then use the method like this. Don't even bother to inspect the error object unless the method returns nil:
// initialize NSError object
NSError* error = nil;
// try to feed the world
id yayOrNay = [self endWorldHunger:smallAmountsOfMonies error:&error];
if (!yayOrNay) {
// inspect error
NSLog(#"%#", [error localizedDescription]);
}
// otherwise the world has been fed. Wow, your code must rock.
We were able to access the error's localizedDescription because we set a value for NSLocalizedDescriptionKey.
The best place for more information is Apple's documentation. It really is good.
There is also a nice, simple tutorial on Cocoa Is My Girlfriend.
I would like to add some more suggestions based on my most recent implementation. I've looked at some code from Apple and I think my code behaves in much the same way.
The posts above already explain how to create NSError objects and return them, so I won't bother with that part. I'll just try to suggest a good way to integrate errors (codes, messages) in your own app.
I recommend creating 1 header that will be an overview of all the errors of your domain (i.e. app, library, etc..). My current header looks like this:
FSError.h
FOUNDATION_EXPORT NSString *const FSMyAppErrorDomain;
enum {
FSUserNotLoggedInError = 1000,
FSUserLogoutFailedError,
FSProfileParsingFailedError,
FSProfileBadLoginError,
FSFNIDParsingFailedError,
};
FSError.m
#import "FSError.h"
NSString *const FSMyAppErrorDomain = #"com.felis.myapp";
Now when using the above values for errors, Apple will create some basic standard error message for your app. An error could be created like the following:
+ (FSProfileInfo *)profileInfoWithData:(NSData *)data error:(NSError **)error
{
FSProfileInfo *profileInfo = [[FSProfileInfo alloc] init];
if (profileInfo)
{
/* ... lots of parsing code here ... */
if (profileInfo.username == nil)
{
*error = [NSError errorWithDomain:FSMyAppErrorDomain code:FSProfileParsingFailedError userInfo:nil];
return nil;
}
}
return profileInfo;
}
The standard Apple-generated error message (error.localizedDescription) for the above code will look like the following:
Error Domain=com.felis.myapp Code=1002 "The operation couldn’t be completed. (com.felis.myapp error 1002.)"
The above is already quite helpful for a developer, since the message displays the domain where the error occured and the corresponding error code. End users will have no clue what error code 1002 means though, so now we need to implement some nice messages for each code.
For the error messages we have to keep localisation in mind (even if we don't implement localized messages right away). I've used the following approach in my current project:
1) create a strings file that will contain the errors. Strings files are easily localizable. The file could look like the following:
FSError.strings
"1000" = "User not logged in.";
"1001" = "Logout failed.";
"1002" = "Parser failed.";
"1003" = "Incorrect username or password.";
"1004" = "Failed to parse FNID."
2) Add macros to convert integer codes to localized error messages. I've used 2 macros in my Constants+Macros.h file. I always include this file in the prefix header (MyApp-Prefix.pch) for convenience.
Constants+Macros.h
// error handling ...
#define FS_ERROR_KEY(code) [NSString stringWithFormat:#"%d", code]
#define FS_ERROR_LOCALIZED_DESCRIPTION(code) NSLocalizedStringFromTable(FS_ERROR_KEY(code), #"FSError", nil)
3) Now it's easy to show a user friendly error message based on an error code. An example:
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error"
message:FS_ERROR_LOCALIZED_DESCRIPTION(error.code)
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alert show];
Great answer Alex. One potential issue is the NULL dereference. Apple's reference on Creating and Returning NSError objects
...
[details setValue:#"ran out of money" forKey:NSLocalizedDescriptionKey];
if (error != NULL) {
// populate the error object with the details
*error = [NSError errorWithDomain:#"world" code:200 userInfo:details];
}
// we couldn't feed the world's children...return nil..sniffle...sniffle
return nil;
...
Objective-C
NSError *err = [NSError errorWithDomain:#"some_domain"
code:100
userInfo:#{
NSLocalizedDescriptionKey:#"Something went wrong"
}];
Swift 3
let error = NSError(domain: "some_domain",
code: 100,
userInfo: [NSLocalizedDescriptionKey: "Something went wrong"])
Please refer following tutorial
i hope it will helpful for you but prior you have to read documentation of NSError
This is very interesting link i found recently ErrorHandling
I'll try summarize the great answer by Alex and the jlmendezbonini's point, adding a modification that will make everything ARC compatible (so far it's not since ARC will complain since you should return id, which means "any object", but BOOL is not an object type).
- (BOOL) endWorldHunger:(id)largeAmountsOfMonies error:(NSError**)error {
// begin feeding the world's children...
// it's all going well until....
if (ohNoImOutOfMonies) {
// sad, we can't solve world hunger, but we can let people know what went wrong!
// init dictionary to be used to populate error object
NSMutableDictionary* details = [NSMutableDictionary dictionary];
[details setValue:#"ran out of money" forKey:NSLocalizedDescriptionKey];
// populate the error object with the details
if (error != NULL) {
// populate the error object with the details
*error = [NSError errorWithDomain:#"world" code:200 userInfo:details];
}
// we couldn't feed the world's children...return nil..sniffle...sniffle
return NO;
}
// wohoo! We fed the world's children. The world is now in lots of debt. But who cares?
return YES;
}
Now instead of checking for the return value of our method call, we check whether error is still nil. If it's not we have a problem.
// initialize NSError object
NSError* error = nil;
// try to feed the world
BOOL success = [self endWorldHunger:smallAmountsOfMonies error:&error];
if (!success) {
// inspect error
NSLog(#"%#", [error localizedDescription]);
}
// otherwise the world has been fed. Wow, your code must rock.
Another design pattern that I have seen involves using blocks, which is especially useful when a method is being run asynchronously.
Say we have the following error codes defined:
typedef NS_ENUM(NSInteger, MyErrorCodes) {
MyErrorCodesEmptyString = 500,
MyErrorCodesInvalidURL,
MyErrorCodesUnableToReachHost,
};
You would define your method that can raise an error like so:
- (void)getContentsOfURL:(NSString *)path success:(void(^)(NSString *html))success failure:(void(^)(NSError *error))failure {
if (path.length == 0) {
if (failure) {
failure([NSError errorWithDomain:#"com.example" code:MyErrorCodesEmptyString userInfo:nil]);
}
return;
}
NSString *htmlContents = #"";
// Exercise for the reader: get the contents at that URL or raise another error.
if (success) {
success(htmlContents);
}
}
And then when you call it, you don't need to worry about declaring the NSError object (code completion will do it for you), or checking the returning value. You can just supply two blocks: one that will get called when there is an exception, and one that gets called when it succeeds:
[self getContentsOfURL:#"http://google.com" success:^(NSString *html) {
NSLog(#"Contents: %#", html);
} failure:^(NSError *error) {
NSLog(#"Failed to get contents: %#", error);
if (error.code == MyErrorCodesEmptyString) { // make sure to check the domain too
NSLog(#"You must provide a non-empty string");
}
}];
extension NSError {
static func defaultError() -> NSError {
return NSError(domain: "com.app.error.domain", code: 0, userInfo: [NSLocalizedDescriptionKey: "Something went wrong."])
}
}
which I can use NSError.defaultError() whenever I don't have valid error object.
let error = NSError.defaultError()
print(error.localizedDescription) //Something went wrong.
Well it's a little bit out of question scope but in case you don't have an option for NSError you can always display the Low level error:
NSLog(#"Error = %# ",[NSString stringWithUTF8String:strerror(errno)]);