[置顶] IOS KeyChain理解及代码事例

对KeyChain的理解，可参照http://my.oschina.net/w11h22j33/blog/206713

文中利用KeyChain保存用户名和密码，用户名放在属性中，密码放在密码项中；其中对KeyChain项的增删改查，我个人觉得是有问题的，为了方面自己代码上的使用，也帮助阅读该文的其他读者更好的理解，我修正了代码如下：

</pre><p></p><p><pre name="code" class="objc">//存储/增加
-(IBAction)saveClicked:(id)sender{
    
    if(_nameTF.text.length > 0 && _psdTF.text.length > 0) {
        NSMutableDictionary* dic = [NSMutableDictionary dictionary];
        
        [dic setObject:(__bridge_transfer id)kSecClassGenericPassword forKey:(__bridge_transfer id)kSecClass];
        [dic setObject:_nameTF.text forKey:(__bridge_transfer id)kSecAttrAccount];
        [dic setObject:[_psdTF.text dataUsingEncoding:NSUTF8StringEncoding] forKey:(__bridge_transfer id)kSecValueData];
        
        OSStatus s = SecItemAdd((__bridge_retained CFDictionaryRef)dic, NULL);
        NSLog(@"%d",s);
    }

}

//获取/查询
-(IBAction)showClicked:(id)sender
{
    if(_nameTF.text.length > 0) {
        NSDictionary* query = [NSDictionary dictionaryWithObjectsAndKeys:
                               (__bridge_transfer id)kSecClassGenericPassword, (__bridge_transfer id)kSecClass,
                               _nameTF.text, (__bridge_transfer id)kSecAttrAccount,
                               kCFBooleanTrue, kSecReturnAttributes,nil];
        
        CFTypeRef result = nil;
        OSStatus s = SecItemCopyMatching((__bridge_retained CFDictionaryRef)query, &result);
        
        NSLog(@"%d",s);
        NSLog(@"%@",result);
        
        if(s == noErr) {//通过用户名判断item项是否存在
            NSMutableDictionary* dic = [NSMutableDictionary dictionary];
            [dic setObject:_nameTF.text forKey: (__bridge_transfer id)kSecAttrAccount];
            [dic setObject:(__bridge_transfer id)kCFBooleanTrue forKey:(__bridge_transfer id)kSecReturnData];
            [dic setObject:(__bridge_transfer id)kSecClassGenericPassword forKey:(__bridge_transfer id)kSecClass];
            
            CFDataRef dataRef = NULL;
            if(SecItemCopyMatching((__bridge_retained CFDictionaryRef)dic, (CFTypeRef*)&dataRef) == noErr) {
                
                NSData *data = (__bridge_transfer id)dataRef;
                NSLog(@"%ld", data.length);
                
                NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
            }
        }
    }else{
        
        NSDictionary* query = [NSDictionary dictionaryWithObjectsAndKeys:
                               (__bridge_transfer id)kSecClassGenericPassword,(__bridge_transfer id)kSecClass,
                               (__bridge_transfer id)kSecMatchLimitAll, (__bridge_transfer id)kSecMatchLimit,
                               (__bridge_transfer id)kCFBooleanTrue,(__bridge_transfer id)kSecReturnAttributes,nil];
        
        CFArrayRef result = NULL;
        OSStatus s = SecItemCopyMatching((__bridge_retained CFDictionaryRef)query, (CFTypeRef*)&result);
        
        NSArray *array = (__bridge_transfer NSArray*)result;//(可以遍历所有keychain项)
        
        NSLog(@"%d",s);
        NSLog(@"%@",result);
    }
    

    
}

//删除
-(IBAction)delClicked:(id)sender{
    
    if(_nameTF.text.length > 0){
        NSDictionary* query = [NSDictionary dictionaryWithObjectsAndKeys:(__bridge_transfer id)kSecClassGenericPassword,kSecClass,
                               _nameTF.text,kSecAttrAccount,nil];
        OSStatus status = SecItemDelete((__bridge_retained CFDictionaryRef)query);
        NSLog(@"%d",status);
    }

}

//改
-(IBAction)modifyClicked:(id)sender{
    
    if(_nameTF.text.length > 0 && _psdTF.text.length > 0) {
        NSDictionary* query = [NSDictionary dictionaryWithObjectsAndKeys:
                               (__bridge_transfer id)kSecClassGenericPassword, (__bridge_transfer id)kSecClass,
                               _nameTF.text, (__bridge_transfer id)kSecAttrAccount,
                               (__bridge_transfer id)kCFBooleanTrue, (__bridge_transfer id)kSecReturnAttributes,nil];
        
        CFTypeRef result = nil;
        if(SecItemCopyMatching((__bridge_retained CFDictionaryRef)query, &result) == noErr)//存在才修改
        {
            //设置需要更新的属性列表，一定要删除kSecClass，因为不能update不该字段，否则会报错
            NSMutableDictionary* update = [[NSMutableDictionary alloc]init];
            [update setObject:[_psdTF.text dataUsingEncoding:NSUTF8StringEncoding] forKey:(__bridge_transfer id)kSecValueData];
            [update removeObjectForKey:(__bridge_transfer id)kSecClass];
            
            //设置查找条件，即根据这个条件找到keychain项
            NSMutableDictionary* updateItem = [[NSMutableDictionary alloc]init];
            [updateItem setObject:[query objectForKey:(__bridge_transfer id)kSecClass] forKey:(__bridge_transfer id)kSecClass];
            [updateItem setObject:_nameTF.text forKey:(__bridge_transfer id)kSecAttrAccount];
            
            //参数一表示要查虚的，参数二表示更新后的值
            OSStatus status = SecItemUpdate((__bridge_retained CFDictionaryRef)updateItem, (__bridge_retained CFDictionaryRef)update);
            NSLog(@"%d",status);
        }
    }
}