小编t0a*_*0a0的帖子

在ios8上,我正在使用核心数据表视图控制器,删除行后,我的部分页脚视图突然一直向下到底部UITableView.当我滚动表格视图时,页脚视图会返回到它的位置.如何解决这个问题,为什么会发生这种情况？

以下是代码以防万一.

- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{       
    if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
    {
        switch(type)
        {
            case NSFetchedResultsChangeInsert:
                [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeDelete:
                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
                break;

            case NSFetchedResultsChangeUpdate:
                [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeMove:
                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;
        }
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    if (self.beganUpdates)
    {
       [self.tableView endUpdates];
    }
}

有一个PFQuery的方法

PFQuery *query = [PFQuery queryWithClassName:@"class"];
[query whereKey:(NSString *)key containsAllObjectsInArray:(NSArray *)array];

是否有类似的方法来定义数组中是否有指定的对象？喜欢

[query whereKey:(NSString *)key doesNotContainAllObjectsInArray:(NSArray *)array];

如果不是,如何自己编写此方法？

当用户触摸UIButton时,它会变灰.什么苹果能做到这样的效果？当我的自定义UIButton突出显示时,我需要相同的效果.

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    AppDelegate* appDelegate=(AppDelegate*)[UIApplication sharedApplication].delegate;
    if ([keyPath isEqualToString:@"highlighted"]){
        UIButton *button = object;
        if (button.isHighlighted) {
            self.backgroundColor=[UIColor colorWithRed:36.0/255.0 green:153.0/255.0 blue:116.0/255.0 alpha:1];
        }else{
            self.backgroundColor=appDelegate.currentAppColor;
        }
    }
}

我使用此代码,但更改背景颜色不会影响任何子视图.我也需要它们变灰.

我正在创建一个性能高的应用程序，并且想知道编写相同代码的哪种方式在运行时运行得更快。

选项1：

let a = 1 + 2
self.doSomething(with: a)
self.doSomethingElse(with: a)

选项2：

self.doSomething(with: 1 + 2)
self.doSomethingElse(with: 1 + 2)

如果任何一个选项都更快，那么对结构体也是如此吗？例如

let a = CGPoint(x: 1, y: 1)
self.doSomething(with: a)
self.doSomethingElse(with: a)

要么

self.doSomething(with: CGPoint(x: 1, y: 1))
self.doSomethingElse(with: CGPoint(x: 1, y: 1))

编辑：添加了真实的场景

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {
      return
    }

    let currentPoint = touch.location(in: view)
    let lastPoint = touch.previousLocation(in: view)


    //////////

    let newPoint1 = CGPoint(x: lastPoint.x - …