iOS - 解析 - PFQuery 不起作用
-
02-01-2020 - |
题
我正在创建一个自定义类 ChatRequest
, ,但是当我尝试查询它时,它不会返回任何自定义键。
这是我的代码:
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
PFQuery *query = [PFQuery queryWithClassName:@"ChatRequest"];
[query setValue:[PFUser currentUser].username forKey:@"toUser"];
NSArray *objects = [query findObjects];
for (NSUInteger i = 0; i < objects.count; i++) {
PFObject *object = [objects objectAtIndex:i];
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Chat Request!" message:object.sendingUser + @"wants to chat with you!" delegate:self cancelButtonTitle:@"Decline" otherButtonTitles:@"Accept", nil];
[alertView show];
}
}
有人可以帮忙吗?我检查了我的类是否正确并且钥匙在那里,但它仍然无法工作。
解决方案
你不使用 setValue
向查询添加约束。你用 whereKey:equalTo:
, ,所以你的代码应该是:
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
PFQuery *query = [PFQuery queryWithClassName:@"ChatRequest"];
[query whereKey:@"toUser" equalTo:[PFUser currentUser].username ];
NSArray *objects = [query findObjects];
for (NSUInteger i = 0; i < objects.count; i++) {
PFObject *object = [objects objectAtIndex:i];
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Chat Request!" message:object.sendingUser + @"wants to chat with you!" delegate:self cancelButtonTitle:@"Decline" otherButtonTitles:@"Accept", nil];
[alertView show];
}
}
然而,出于性能原因,像这样同步调用查找对象是一个坏主意。你应该使用 - (void)findObjectsInBackgroundWithBlock:(PFArrayResultBlock)block
允许查询在后台完成。在完成块中,您可以刷新 UI。
另外,从设计的角度来看,您的 toUser
应该是引用类型列,而不是字符串类型。然后你可以使用
[query whereKey:@"toUser" equalTo:[PFUser currentUser]];
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