FacebFacebook 处理自动登录问题（iOS）

在本地保存密码的工具

我们可以直接使用facebook的官方demo里面的两个类来管理我们的密码

一定要添加Security.framework这个依赖库

SUCacheItem这个类实现了协议，对 profile和token进行归档和反归档。

@interface SUCacheItem : NSObject<NSSecureCoding>

@property (nonatomic, strong) FBSDKProfile *profile;
@property (nonatomic, strong) FBSDKAccessToken *token;

@end

SUCache这个类用来对SUCacheItem进行增删改查操作。

#import "SUCacheItem.h"

// A helper class to store items in keychain.
@interface SUCache : NSObject

+ (SUCacheItem *)itemForSlot:(NSInteger)slot;
+ (void)saveItem:(SUCacheItem *)item slot:(NSInteger)slot;
+ (void)deleteItemInSlot:(NSInteger)slot;
+ (void)clearCache;

@end

登录

现在的登录逻辑需要改一下，我们先判断一下本地储存token没有，如果本地游储存，判断是否是有效的，如果有效，就直接登录进去。如果无效了，就删除本地的token，进行登录操作。
代码修改成下面这样。

#pragma mark - login
//自定义login button的点击事件
- (IBAction)loginBtnClicked:(id)sender {
    NSInteger slot = 0;
    FBSDKAccessToken *token = [SUCache itemForSlot:slot].token;
    if (token) {
        [self autoLoginWithToken:token];
    }
    else {
        [self newLogin];
    }

}

- (void)autoLoginWithToken:(FBSDKAccessToken *)token {
    [FBSDKAccessToken setCurrentAccessToken:token];
    FBSDKGraphRequest *request = [[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:nil];
    [request startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
        //token过期，删除存储的token和profile
        if (error) {
            NSLog(@"The user token is no longer valid.");
            NSInteger slot = 0;
            [SUCache deleteItemInSlot:slot];
            [FBSDKAccessToken setCurrentAccessToken:nil];
            [FBSDKProfile setCurrentProfile:nil];
        }
        //做登录完成的操作
        else {

        }
    }];
}

- (void)newLogin {
    FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];
    [login
     logInWithReadPermissions: @[@"public_profile"]
     fromViewController:self
     handler:^(FBSDKLoginManagerLoginResult *result, NSError *error) {
         NSLog(@"facebook login result.grantedPermissions = %@,error = %@",result.grantedPermissions,error);
         if (error) {
             NSLog(@"Process error");
         } else if (result.isCancelled) {
             NSLog(@"Cancelled");
         } else {
             NSLog(@"Logged in");
         }
     }];
}

token 和 profile的保存

在通知事件里如果获取到了新的token或者profile，就把它们保存到SUCacheItem的实例中去。

注册通知

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(_updateContent:)
                                                 name:FBSDKProfileDidChangeNotification
                                               object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(_accessTokenChanged:)
                                                 name:FBSDKAccessTokenDidChangeNotification
                                               object:nil];

在通知的事件中处理token和profile的保存

#pragma mark - Notification

- (void)_updateContent:(NSNotification *)notification {
    FBSDKProfile *profile = notification.userInfo[FBSDKProfileChangeNewKey];
    [self labelDisplayWithProfile:profile];
}

- (void)_accessTokenChanged:(NSNotification *)notification
{
    FBSDKAccessToken *token = notification.userInfo[FBSDKAccessTokenChangeNewKey];
    if (!token) {
        [FBSDKAccessToken setCurrentAccessToken:nil];
        [FBSDKProfile setCurrentProfile:nil];
    } else {
        NSInteger slot = 0;
        SUCacheItem *item = [SUCache itemForSlot:slot] ?: [[SUCacheItem alloc] init];
        if (![item.token isEqualToAccessToken:token]) {
            item.token = token;
            [SUCache saveItem:item slot:slot];
        }
    }
}