How to align components to grid?

问题:

I'm working on an application where users can put their own controls on a view. Now I'm working on the details where I want the controls to be aligned to a sort of grid.

1. How can I draw a grid?
2. How can I make sure the controls are aligned automatically to the grid (to the closest corner?)

Thanks in advance!

anyone who can help?

回答1:

For those who are still interested in the answer:

I first drew the horizontal and vertical line:

-(void)drawGrid {

for(int y=self.gridSize;y<self.templateEditView.frame.size.height;y+=self.gridSize){
    UIView *hline = [[UIView alloc] init];
    [hline setBackgroundColor:[[UIColor blackColor] colorWithAlphaComponent:0.1f]];
    hline.frame = CGRectMake(0, y, self.templateEditView.frame.size.width, 1);
    [self.templateEditView addSubview:hline];
}

for(int x=self.gridSize;x<self.templateEditView.frame.size.width;x+=self.gridSize){
    UIView *vline = [[UIView alloc] init];
    [vline setBackgroundColor:[[UIColor blackColor] colorWithAlphaComponent:0.1f]];
    vline.frame = CGRectMake(x, 0, 1, self.templateEditView.frame.size.height);
    [self.templateEditView addSubview:vline];
}

}

When one of the objects is dragged and dropped, They have to align to the grid:

-(void)alignToGrid:(UIView *)control{

int gridSize = self.gridSize;

int oldX = (int)control.frame.origin.x;
int newX = (oldX /gridSize)*gridSize;
if(oldX%gridSize > gridSize/2){
    newX+=gridSize;
}

int oldY = (int)control.frame.origin.y;
int newY = (oldY /gridSize)*gridSize;
if(oldY%gridSize > gridSize/2){
    newY+=gridSize;
}

[UIView animateWithDuration:0.3f delay:0.0f options:UIViewAnimationOptionCurveLinear animations:^ {
    [control setFrame: CGRectMake(newX,newY,control.frame.size.width,control.frame.size.height)];
} completion:nil];

}