View controller not in view hierarchy? - mysql

Question

So I am trying to transition from one view controller to another with a segue programmatically so that I can only initialize it when a user needs to login. However, xcode keeps giving me the error that it is not in the view hierarchy and refuses to load to it.
ViewController.h
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController
#end
ViewController.m
#import "ViewController.h"
#import "API.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
if (![[API sharedInstance] isAuthorized]) {
[self performSegueWithIdentifier:#"ShowLogin" sender:nil];
}// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
LoginScreen.h (the controller not in the hierarchy)
#import <UIKit/UIKit.h>
#interface LoginScreen : UIViewController
{
//the login form fields
IBOutlet UITextField *fldUsername;
IBOutlet UITextField *fldPassword;
}
//action for when either button is pressed
-(IBAction)btnLoginRegisterTapped:(id)sender;
#end
LoginScreen.m (the controller apparently not in the hierarchy)
#import "LoginScreen.h"
#import "UIAlertView+error.h"
#import "API.h"
#include <CommonCrypto/CommonDigest.h>
#define kSalt #"(protected value)"
#implementation LoginScreen
-(void)viewDidLoad {
[super viewDidLoad];
}
#pragma mark - View lifecycle
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
-(IBAction)btnLoginRegisterTapped:(UIButton*)sender {
//form fields validation
if (fldUsername.text.length < 4 || fldPassword.text.length < 4) {
[UIAlertView error:#"Enter username and password over 4 chars each."];
return;
}
//salt the password
NSString* saltedPassword = [NSString stringWithFormat:#"%#%#", fldPassword.text, kSalt];
//prepare the hashed storage
NSString* hashedPassword = nil;
unsigned char hashedPasswordData[CC_SHA1_DIGEST_LENGTH];
//hash the pass
NSData *data = [saltedPassword dataUsingEncoding: NSUTF8StringEncoding];
if (CC_SHA1([data bytes], [data length], hashedPasswordData)) {
hashedPassword = [[NSString alloc] initWithBytes:hashedPasswordData length:sizeof(hashedPasswordData) encoding:NSASCIIStringEncoding];
} else {
[UIAlertView error:#"Password can't be sent"];
return;
}
//check whether it's a login or register
NSString* command = (sender.tag==1)?#"register":#"login";
NSMutableDictionary* params =[NSMutableDictionary dictionaryWithObjectsAndKeys:command, #"command", fldUsername.text, #"username", hashedPassword, #"password", nil];
//make the call to the web API
[[API sharedInstance] commandWithParams:params onCompletion:^(NSDictionary *json) {
//result returned
NSDictionary* res = [[json objectForKey:#"result"] objectAtIndex:0];
if ([json objectForKey:#"error"]==nil && [[res objectForKey:#"IdUser"] intValue]>0) {
[[API sharedInstance] setUser: res];
[self.presentingViewController dismissViewControllerAnimated:YES completion:nil];
//show message to the user
[[[UIAlertView alloc] initWithTitle:#"Logged in" message:[NSString stringWithFormat:#"Welcome %#",[res objectForKey:#"username"]] delegate:nil cancelButtonTitle:#"Close" otherButtonTitles: nil] show];
} else {
//error
[UIAlertView error:[json objectForKey:#"error"]];
}
}];
}
#end
API.h (calling my web service)
#import "AFHTTPClient.h"
#import "AFNetworking.h"
typedef void (^JSONResponseBlock)(NSDictionary* json);
#interface API : AFHTTPClient
#property (strong, nonatomic) NSDictionary* user;
+(API*)sharedInstance;
//check whether there's an authorized user
-(BOOL)isAuthorized;
//send an API command to the server
-(void)commandWithParams:(NSMutableDictionary*)params onCompletion:(JSONResponseBlock)completionBlock;
-(NSURL*)urlForImageWithId:(NSNumber*)IdPhoto isThumb:(BOOL)isThumb;
#end
API.m (calling my web service)
#import "API.h"
//the web location of the service
#define kAPIHost #"(protected web address)"
#define kAPIPath #""
#implementation API
#synthesize user;
#pragma mark - Singleton methods
/**
* Singleton methods
*/
+(API*)sharedInstance {
static API *sharedInstance = nil;
static dispatch_once_t oncePredicate;
dispatch_once(&oncePredicate, ^{
sharedInstance = [[self alloc] initWithBaseURL:[NSURL URLWithString:kAPIHost]];
});
return sharedInstance;
}
#pragma mark - init
//intialize the API class with the deistination host name
-(API*)init {
//call super init
self = [super init];
if (self != nil) {
//initialize the object
user = nil;
[self registerHTTPOperationClass:[AFJSONRequestOperation class]];
// Accept HTTP Header; see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1
[self setDefaultHeader:#"Accept" value:#"application/json"];
}
return self;
}
-(BOOL)isAuthorized {
return [[user objectForKey:#"IdUser"] intValue]>0;
}
-(void)commandWithParams:(NSMutableDictionary*)params onCompletion:(JSONResponseBlock)completionBlock {
NSData* uploadFile = nil;
if ([params objectForKey:#"file"]) {
uploadFile = (NSData*)[params objectForKey:#"file"];
[params removeObjectForKey:#"file"];
}
NSMutableURLRequest *apiRequest = [self multipartFormRequestWithMethod:#"POST" path:kAPIPath parameters:params constructingBodyWithBlock: ^(id <AFMultipartFormData>formData) {
if (uploadFile) {
[formData appendPartWithFileData:uploadFile name:#"file" fileName:#"photo.jpg" mimeType:#"image/jpeg"];
}
}];
AFJSONRequestOperation* operation = [[AFJSONRequestOperation alloc] initWithRequest: apiRequest];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
//success!
completionBlock(responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//failure :(
completionBlock([NSDictionary dictionaryWithObject:[error localizedDescription] forKey:#"error"]);
}];
[operation start];
}
-(NSURL*)urlForImageWithId:(NSNumber*)IdPhoto isThumb:(BOOL)isThumb {
NSString* urlString = [NSString stringWithFormat:#"%#/%#upload/%#%#.jpg", kAPIHost, kAPIPath, IdPhoto, (isThumb)?#"-thumb":#""];
return [NSURL URLWithString:urlString];
}
#end

Answer 1

The issue is that the view of your initial view controller has not been added to the window by the time viewDidLoad is called.
Move that call to viewDidAppear:
-(void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
if (![[API sharedInstance] isAuthorized]) {
[self performSegueWithIdentifier:#"ShowLogin" sender:self];
}
}