上篇文章向大家介紹了VFL的基本的語法點，假設對下面演示樣例不熟的童鞋，能夠前去參考。廢話不多說。我們直接來看演示樣例。

演示樣例一

將五個大小同樣、顏色不同的view排成一行，view間的間隔為15px,第一個view的間隔與屏幕的左邊間隔10px,最後一個view的間隔與屏幕的右邊間隔也為10px。

//依據屏幕的寬度。計算view的寬度和高度
    CGFloat width = ([[UIScreen mainScreen] bounds].size.width-2*10-4*15)/5;
    CGFloat height = width;

    //固定第一個view
 

    UIView *firstView = [UIView new];
    firstView.backgroundColor = [UIColor blackColor];
    // 將次屬性設置為NO,表示將使用AutoLayout的方式來布局
    firstView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:firstView];

    //------使用VFL為第一個view加入約束------
    //在水平方向上，讓firstview的左邊與父視圖的左邊間隔10px,且自身寬度為width
 

    NSArray *constraints1 = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[firstView(==width)]" options:0 metrics:@{@"width":@(width)} views:NSDictionaryOfVariableBindings(firstView)];
    //在垂直方向上，讓firstView的上邊與父視圖的上邊間隔100px,且自身的高度為height
    NSArray *constraints2 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[firstView(==height)]"
 
 options:0 metrics:@{@"height":@(height)} views:NSDictionaryOfVariableBindings(firstView)];
    [self.view addConstraints:constraints1];
    [self.view addConstraints:constraints2];

    //定義一個顏色數組
    NSArray *colors = @[[UIColor redColor],[UIColor orangeColor],[UIColor yellowColor],[UIColor blueColor]];
    //定義一個views數組
    NSMutableArray *views = [NSMutableArray array];
    [views addObject:firstView];
    for (int i = 0; i < 4; i++) {
        UIView *view = [UIView new];
        view.backgroundColor = colors[i];
         view.translatesAutoresizingMaskIntoConstraints = NO;
        [self.view addSubview:view];
        [views addObject:view];
    }

    //依次給views數組中的view使用vfl加入約束
    for (int i = 1; i < views.count; i++) {
        UIView *view1 = views[i-1];
        UIView *view2 = views[i];
        NSDictionary *bindings = NSDictionaryOfVariableBindings(view1,view2);
        NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:[view1]-15-[view2(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width]} views:bindings];
        [self.view addConstraints:constraints];

    }
    UIView *view1 = views[0];
    for (int i = 0; i < views.count; i++) {
        UIView *view2 = views[i];
        NSDictionary *bindings = NSDictionaryOfVariableBindings(view1,view2);
        NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[view2(==view1)]" options:0 metrics:nil views:bindings];
        [self.view addConstraints:constraints];

    }

效果截圖:

下篇演示樣例將會是使用VFL對登錄界面進行布局，喜歡我的博客的童鞋能夠關註一波！

VFL演示樣例