我有一个包含用户帖子的表格 View 。每个帖子都有图片、用户名和帖子本身。刷新控件的操作是使用来自 Parse 的数据重新加载表。除了拉动刷新时的极度延迟外，一切都完美无缺。不知道是因为每个单元格里的图片还是别的原因。如果有人知道为什么会发生这种情况，请告诉我。如果有人需要，我会发布代码。
-(void)viewDidLoad {
refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:@selector(retrieveFromParse) forControlEvents:UIControlEventValueChanged];
refreshControl.backgroundColor = [UIColor whiteColor];
refreshControl.tintColor = [UIColor colorWithRed:0.3878 green:0.5686 blue:1.0 alpha:0.9];
[userPostsTable addSubview:refreshControl];
}
-(void) retrieveFromParse {
PFQuery *quoteQuery = [PFQuery queryWithClassName:@"Quotes"];
quoteQuery.cachePolicy = kPFCachePolicyCacheThenNetwork;
[quoteQuery orderByDescending:@"createdAt"];
[quoteQuery getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error) {
if (!error) {
NSString *category = [object objectForKey:@"Category"];
if (category == nil) {
quoteLabel.font = [UIFont fontWithName:@"Helvetica Neue Light Italic" size:15];
}
else {
quoteLabel.font = [UIFont fontWithName:@"Helvetica Neue" size:15];
}
quoteString = [object objectForKey:@"quoteContent"];
quoteLabel.text = quoteString;
quoteIdString = object.objectId;
[refreshControl endRefreshing];
}
else {
[refreshControl endRefreshing];
}
}];
PFQuery *userPostsQuery = [PFQuery queryWithClassName:@"userPosts"];
userPostsQuery.cachePolicy = kPFCachePolicyCacheThenNetwork;
[userPostsQuery setLimit:300];
[userPostsQuery whereKey:@"quoteObjectId" matchesKey:@"objectId" inQuery:quoteQuery];
if (segmentedControl.selectedSegmentIndex == 0) {
[userPostsQuery orderByDescending:@"createdAt"];
}
else {
[userPostsQuery orderByDescending:@"likeCount"];
}
[userPostsQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
userPostsArray = [[NSArray alloc] initWithArray:objects];
[userPostsTable reloadData];
[refreshControl endRefreshing];
}
else {
[refreshControl endRefreshing];
}
}];
}
最佳答案
您正在后台线程中检索对象。
getFirstObjectInBackgroundWithBlock:
您还试图从后台线程更新您的用户界面。您只需要从主线程更新 UI:
调用所有与 UI 相关的调用，例如:
[userPostsTable reloadData];
[refreshControl endRefreshing];
仅来自主线程。
使用:
dispatch_async(dispatch_get_main_queue(), ^{
// Update UI
});
关于ios - UIRefreshControl 滞后，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27673599/