Ios7 Parse.com查询10000(10K)个对象
我有一个parse数据库,其中一个名为Ios7 Parse.com查询10000(10K)个对象,ios7,xcode5,parse-platform,Ios7,Xcode5,Parse Platform,我有一个parse数据库,其中一个名为MeetingObject的类填充了6000个对象(顺便说一下,它会增长…) 作为解析查询限制1000,我尝试使用skip query属性获取它们 以下代码为我提供了2000个对象: NSMutableArray *allObjects = [NSMutableArray array]; NSUInteger limit = 1000; __block NSUInteger skip = 0; [query setLimit: limit]; [query
MeetingObject
的类填充了6000个对象(顺便说一下,它会增长…)
作为解析查询限制1000,我尝试使用skip query属性获取它们
以下代码为我提供了2000个对象:
NSMutableArray *allObjects = [NSMutableArray array];
NSUInteger limit = 1000;
__block NSUInteger skip = 0;
[query setLimit: limit];
[query setSkip: skip];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
if (objects.count == limit) {
// There might be more objects in the table. Update the skip value and execute the query again.
skip += limit;
[query setSkip: skip];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
}];
}
} else if (error || [error code] == kPFErrorConnectionFailed) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error!" message:NSLocalizedString(@"The Internet connection appears to be offline.",@"no internet") delegate:self cancelButtonTitle:nil otherButtonTitles:@"Ok", nil];
self.navigationItem.rightBarButtonItem.enabled = YES;
self.tableView.userInteractionEnabled = YES;
[alertView show];
return;
}
}];
我的理解是,如果我想获得1000多个对象,我必须添加另一个嵌套查询,然后再添加另一个嵌套查询,以此类推:
// finding the first 1000 objects
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
if (objects.count == limit) {
// finding another 1000 objects
skip += limit;
[query setSkip: skip];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
if (objects.count == limit) {
// finding another 1000 objects
skip += limit;
[query setSkip: skip];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
}];
}
}];
}
但是如果我不知道物体的确切数量呢?我尝试使用:
while (objects.count == limit) {
// There might be more objects in the table. Update the skip value and execute the query again.
skip += limit;
[query setSkip: skip];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
[allObjects addObjectsFromArray:objects];
NSLog(@"%lu", (unsigned long)allObjects.count );
}];
}
但我明白了
*由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序,原因:“此查询具有未完成的网络连接。你必须等到它完成。”
因为查询当然是在最后一个完成之前进行的…我要做的是首先获取对象的数量,然后使用skip方法进行查询
PFQuery *query = [PFQuery queryWithClassName:@"GameScore"];
[query whereKey:@"playername" equalTo:@"Sean Plott"];
[query countObjectsInBackgroundWithBlock:^(int count, NSError *error) {
if (!error) {
dispatchFindObjectsUsingLimit(count)
} else {
// The request failed
}
}];
虽然这是一个迟来的反应,但这可以帮助其他遇到这个问题的人。 基本上,就像上面Simon的回答一样,第1步是获得一个计数,然后创建一个组调度,循环处理每个请求,直到所有数据都下载完毕。这是我使用的(稍微通用的)代码:
- (void)getLargeDataFromParseWithBlock:(void (^)(NSArray *, NSError *))block {
int max = 1000;
__block NSError *error;
PFQuery *query = [PFQuery queryWithClassName:@"<your class>"];
[query whereKey:@"<field name in class>" equalTo:@"xyz"];
query.limit = max;
// get count of ojects first
[query countObjectsInBackgroundWithBlock:^(int count, NSError *_error) {
if (!error) {
// calculate how many requests are need based on count and max
int APIrequests = (count+max-1)/max;
// create a group dispatch
dispatch_group_t downloadGroup = dispatch_group_create();
for (int i=0; i<APIrequests; i++) {
// tell dispatch a task is starting
dispatch_group_enter(downloadGroup);
PFQuery *dispatchQuery = [PFQuery queryWithClassName:@"<your class>"];
[dispatchQuery whereKey:@"<field name in class>" equalTo:@"xyz"];
dispatchQuery.limit = max;
dispatchQuery.skip = i*max;
[dispatchQuery findObjectsInBackgroundWithBlock:^(NSArray *arrayResponse, NSError *_error2) {
if (!_error2) {
NSLog(@"Successfully retrieved %lu.", (unsigned long)arrayResponse.count);
// do something with arrayResponse like add to core data or sqlite
// tell dispatch task has completed
dispatch_group_leave(downloadGroup);
} else {
NSLog(@"Error: %@ %@", _error2, [_error2 userInfo]);
error = _error2;
// tell dispatch task has completed - need to cover suuccess and fail scenarios of parse request
dispatch_group_leave(downloadGroup);
}
}];
}
// called when no more tasks in dispatch
dispatch_group_notify(downloadGroup, dispatch_get_main_queue(), ^{
if (block) {
if (!error) {
// array could contain combined responses - sourced from core data or sqlite for example
block(@[], nil);
} else {
block(nil, error);
}
}
});
}else {
block(nil, _error);
NSLog(@"Count error: %@ %@", _error, [_error userInfo]);
}
}];
}
-(void)getLargeDataFromParseWithBlock:(void(^)(NSArray*,NSError*)块{
int max=1000;
__块N错误*错误;
PFQuery*query=[PFQuery queryWithClassName:@”“;
[查询whereKey:@“equalTo:@“xyz”];
query.limit=max;
//首先获取项目数
[query countObjectsInBackgroundWithBlock:^(整数计数,N错误*\U错误){
如果(!错误){
//根据计数和最大值计算需要多少请求
int API请求=(计数+max-1)/max;
//创建组调度
dispatch_group_t downloadGroup=dispatch_group_create();
对于(int i=0;此链接回答您的问题: