iOS：使对象阵列在屏幕上移动

Question

I am trying to make multiple UILabels (using a for loop and inserting them into an array) move horizontally across the screen. I have the labels, I have the array, but I cannot figure out how to use animations to get them to move. I tried using [self.array setValue @0 forKey:@"XPOSITION"]; but I do not know how to write the x position. Is there no real way to change the x position in an array? Will I have to make each one its own individual thing and use object.frame = CGRectMake(newx,y,w,h); which seems a bit tedious? Thank you in advance!

Answer 1

Following Aderis' advice about setting the center, you have to use a for loop to set the center of each label.

for (UILabel *label in self.array) {
    CGPoint oldCenter = label.center;
    label.center = CGPoint(oldCenter.x + 20, oldCenter.y);
}

Where you would change 20 to be whatever value you actually wanted to change the x coordinate by.

If you want to have it animated, you can use this:

[UIView animateWithDuration:0.2 animations:^{
    for (UILabel *label in self.array) {
        CGPoint oldCenter = label.center;
        label.center = CGPoint(oldCenter.x + 20, oldCenter.y);
    }
}];

Where you would replace 0.2 with the length in seconds you want the animation to last.

Answer 2

You should try using the builtin animation capabilities of UIView . You can do the following code:

[UIView beginAnimations:nil context:nil];

for (UIView* view in myArray)
{
    [view setCenter:thisViewsTargetCenterPoint];
}

[UIView commitAnimations];

In the for loop, you should do all the UI positioning changes you want, and once you call commitAnimations , UIKit will do all the position changes through animations.