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<NSSecureCoding>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NSLog(@"The user token is no longer valid.");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];
}
}
}