ios – 在Parse中获取任意大量的对象

很好的问题,我已经为自己的工作找到了一个很好的解决方案.最快,最有效的解决方法是查询对象计数,如果超过1000,则在同一个表上运行多个查询,每次查询的skip属性增加1000：

通过[query countObjectsInBACkgroundWithBlock]获取记录总数,并使用它来设置’skip’变量.为每1000条记录运行一个新查询,相应地更新skip属性
每个查询返回时正常处理记录.

您还需要一个帮助程序方法来确定所有查询何时完成,并且您已准备好在本地处理完整数据集.

像这样的东西：

//Define these as class-wide variables in your @interface - don't forget to @synthesize them too!
int queriesToComplete;
int completedQueries;
NSMutableArray *completeDataArray = [[NSMutableArray alloc] init];

//Put in your query load function
PFQuery *recordsCountQuery = [PFQuery queryWithClassName:@"YourClassName"];
[recordsCountQuery countObjectsInBACkgroundWithBlock:^(int number,NSError *error) {
    //Determine how many queries to run
    queriesToComplete = (int)ceil(number/1000) + 1;
    //Set the number of completed queries to zero
    completedQueries = 0;
    //Run a chain of queries - be sure to run them in the BACkground to prevent UI lockup
    for (int i = 0; i < queriesToComplete; i++) {
        PFQuery *chainQuery = [PFQuery queryWithClassName:@"YourClassName"];
        //Add your other 'whereKey: equalTo:' type qualifiers here
        chainQuery.limit = 1000;
        chainQuery.skip = (i*1000);
        [chainQuery findObjectsInBACkgroundWithBlock:^(NSArray *objects,NSError *error) {
            //NSLog(@"query done");
            [completeDataArray addObjectsFromArray:[objects copy]];
            completedQueries ++;
            [self pullCompletioncheck];
        }];
    }
}];

- (void)pullCompletioncheck{
    if (self.queriesToComplete == self.completedQueries) {
        //All queries completed.  
        //All data is Now in the completeDataArray

    }
}