我一直在学习Facebook SDK中的一个登录教程。我已经正确地将其编码为使用相同的ViewController和Button登录和注销。我想知道登录Facebook后如何激活另一个ViewController，任何建议都会很好。。。
我有一个LoginViewController，登录后我想启动MainViewController
代码：
AppDelegate.h
#import <UIKit/UIKit.h>
#import <FacebookSDK/FacebookSDK.h>
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
extern NSString *const FBSessionStateChangedNotification;
extern NSString *const SCSessionStateChangedNotification;
- (BOOL)openSessionWithAllowLoginUI:(BOOL)allowLoginUI;
- (void) closeSession;
@end
AppDelegate.m
#import "AppDelegate.h"
@implementation AppDelegate
NSString *const FBSessionStateChangedNotification =
@"com.example.Login:FBSessionStateChangedNotification";
NSString *const SCSessionStateChangedNotification =
@"com.nathancleary.Login:SCSessionStateChangedNotification";
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions: (NSDictionary *)launchOptions
{
// Override point for customization after application launch.
return YES;
}
/*
* If we have a valid session at the time of openURL call, we handle
* Facebook transitions by passing the url argument to handleOpenURL
*/
- (BOOL)application:(UIApplication *)application
openURL:(NSURL *)url
sourceApplication:(NSString *)sourceApplication
annotation:(id)annotation {
// attempt to extract a token from the url
return [FBSession.activeSession handleOpenURL:url];
}
- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
// this means the user switched back to this app without completing
// a login in Safari/Facebook App
if (FBSession.activeSession.state == FBSessionStateCreatedOpening) {
[FBSession.activeSession close]; // so we close our session and start over
}
}
- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
[FBSession.activeSession close];
}
/*
* Callback for session changes.
*/
- (void)sessionStateChanged:(FBSession *)session
state:(FBSessionState) state
error:(NSError *)error
{
switch (state) {
case FBSessionStateOpen:
if (!error) {
// We have a valid session
NSLog(@"User session found");
}
break;
case FBSessionStateClosed:
case FBSessionStateClosedLoginFailed:
[FBSession.activeSession closeAndClearTokenInformation];
break;
default:
break;
}
[[NSNotificationCenter defaultCenter]
postNotificationName:FBSessionStateChangedNotification
object:session];
if (error) {
UIAlertView *alertView = [[UIAlertView alloc]
initWithTitle:@"Error"
message:error.localizedDescription
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alertView show];
}
}
/*
* Opens a Facebook session and optionally shows the login UX.
*/
- (BOOL)openSessionWithAllowLoginUI:(BOOL)allowLoginUI {
NSArray *permissions = [[NSArray alloc] initWithObjects:
@"user_likes",
@"read_stream",
nil];
return [FBSession openActiveSessionWithPermissions:permissions
allowLoginUI:allowLoginUI
completionHandler:^(FBSession *session,
FBSessionState state,
NSError *error) {
[self sessionStateChanged:session
state:state
error:error];
}];
}
- (void) closeSession {
[FBSession.activeSession closeAndClearTokenInformation];
}
@end
LoginViewController.h
#import <UIKit/UIKit.h>
@interface LoginViewController : UIViewController
- (IBAction)authButtonAction:(id)sender;
@property (strong, nonatomic) IBOutlet UIButton *authButton;
@end
LoginViewController.m
#import "LoginViewController.h"
#import "AppDelegate.h"
@interface LoginViewController ()
@end
@implementation LoginViewController
@synthesize authButton;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(sessionStateChanged:)
name:FBSessionStateChangedNotification
object:nil];
// Check the session for a cached token to show the proper authenticated
// UI. However, since this is not user intitiated, do not show the login UX.
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
[appDelegate openSessionWithAllowLoginUI:NO];
}
- (void)viewDidUnload
{
[self setAuthButton:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)sessionStateChanged:(NSNotification*)notification {
if (FBSession.activeSession.isOpen) {
[self.authButton setTitle:@"Logout" forState:UIControlStateNormal];
} else {
[self.authButton setTitle:@"Login" forState:UIControlStateNormal];
}
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (IBAction)authButtonAction:(id)sender {
AppDelegate *appDelegate =
[[UIApplication sharedApplication] delegate];
// If the user is authenticated, log out when the button is clicked.
// If the user is not authenticated, log in when the button is clicked.
if (FBSession.activeSession.isOpen) {
[appDelegate closeSession];
} else {
// The user has initiated a login, so call the openSession method
// and show the login UX if necessary.
[appDelegate openSessionWithAllowLoginUI:YES];
}
}
@end
如果你使用的是Facebook的sdk 3，你可以把它放在完成处理程序调用的方法中：
- (void)openFacebookSession
{
NSArray *permissions = [[NSArray alloc] initWithObjects:
@"user_photos",
nil];
[FBSession openActiveSessionWithPermissions:permissions
allowLoginUI:YES
completionHandler: ^(FBSession *session, FBSessionState state, NSError *error){
[self sessionStateChanged:session state:state error:error];
}];
}
以下是主视图控制器的启动位置：
- (void)sessionStateChanged:(FBSession *)session
state:(FBSessionState) state
error:(NSError *)error
{
switch (state) {
case FBSessionStateOpen:
{
NSLog(@"FBSessionStateOpen");
//[activityIndicator startAnimating];
// initialize the viewcontroller with a little delay, so that the UI displays the changes made above
double delayInSeconds = 0.1;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard"
bundle: nil];
UIViewController *controller = [mainStoryboard instantiateViewControllerWithIdentifier: @"MainViewController"];
[self presentViewController:controller animated:YES completion:nil];
//[activityIndicator stopAnimating];
});
break;
}
case FBSessionStateClosed:
{
NSLog(@"FBSessionStateClosed");
break;
}
case FBSessionStateClosedLoginFailed:
{
[FBSession.activeSession closeAndClearTokenInformation];
NSLog(@"Facebook State Closed or Failed");
break;
}
default:
{
break;
}
}
if (error) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error"
message:error.localizedDescription
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alertView show];
}
}
这个方法是专门为你必须加载一个沉重的主控制器（这就是为什么你可以激活加载指示器）。您可以很容易地修改它以加载一个可以在同一线程中启动的简单线程。