这是很简单的实际。你的做法是正确的，你需要的是你如何转换到这code。我会尽量简化为您服务。我假设一个UIImageView的宽度放大器;高度为100，只要你喜欢你可以改变

It's quite simple actually. Your approach is correct, all you need is how you convert that into code. I will try to simplify this for you. I am assuming a UIImageView's width & height as 100. You can change as you like

-(void)setUI
{
    lastView = nil;   //Declare a UIImageView* as instance var.
    arrayCount = [array count]; //In your case a static count of 3

    for(NSInteger index =0; index < arrayCount; index++)
    {
        UIImageView *view = [[UIImageView alloc] init];
        [self.mainScroll addSubview:view];

        [view setTranslatesAutoresizingMaskIntoConstraints:NO];

        [self.mainScroll addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(100)]-20-|" options:0 metrics:nil views:@{@"view":view}]];

        //--> If view is first then pin the leading edge to main ScrollView otherwise to the last View.
        if(lastView == nil && index == 0) {
            [self.mainScroll addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[view(100)]" options:0 metrics:nil views:@{@"view":view}]];
        }
        else {
            [self.mainScroll addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[lastView]-10-[view(100)]" options:0 metrics:nil views:@{@"lastView":lastView, @"view":view}]];
        }
        //--> If View is last then pin the trailing edge to mainScrollView trailing edge.
        if(index == arrayCount-1) {
            [self.mainScroll addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[view]-10-|" options:0 metrics:nil views:@{@"view":view}]];
        }
        //--> Assign the current View as last view to keep the reference for next View.
        lastView = view;
    }
}