Autolayout代码编写基本使用
第一种
代码如下：
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| UIView *redView = [[UIView alloc] init];
redView.translatesAutoresizingMaskIntoConstraints = NO;
redView.backgroundColor = UIColor.redColor;
[self.view addSubview:redView];
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| //设置高度
[redView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:40.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeading multiplier:1.0 constant:20.0]];
//设定顶边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:20.0]];
//设置右边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:-20.0]];
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换做使用VFL的话，代码如下：
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| NSDictionary *views = NSDictionaryOfVariableBindings(redView);
CGFloat height = 40;
CGFloat margin = 20;
NSDictionary *metrics = @{ @"margin":@(margin), @"height":@(height) };
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(margin)-[redView]-(margin)-|" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[redView(==height)]" options:0 metrics:metrics views:views]];
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第二种
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| UIView *redView = [[UIView alloc] init];
redView.translatesAutoresizingMaskIntoConstraints = NO;
redView.backgroundColor = UIColor.redColor;
[self.view addSubview:redView];
UIView *blueView = [[UIView alloc] init];
blueView.translatesAutoresizingMaskIntoConstraints = NO;
blueView.backgroundColor = UIColor.blueColor;
[self.view addSubview:blueView];
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| //创建redView的约束
//设置高度
[redView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:40.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeading multiplier:1.0 constant:20.0]];
//设定顶边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:20.0]];
//设定右边边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:-20.0]];
//创建blueView的约束
//设置redView和blueView高度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
//设置redView和blueView的间距为20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:redView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:20.0]];
//让blueView和redView的右对齐
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeRight multiplier:1.0 constant:0.0]];
//blueView的宽度是redView宽度的一半
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:redView attribute:NSLayoutAttributeWidth multiplier:0.5 constant:0.0]];
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第三种
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| UIView *redView = [[UIView alloc] init];
redView.translatesAutoresizingMaskIntoConstraints = NO;
redView.backgroundColor = UIColor.redColor;
[self.view addSubview:redView];
UIView *blueView = [[UIView alloc] init];
blueView.translatesAutoresizingMaskIntoConstraints = NO;
blueView.backgroundColor = UIColor.blueColor;
[self.view addSubview:blueView];
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| //创建redView的约束
//设置高度
[redView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:40.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeading multiplier:1.0 constant:20.0]];
//设定顶边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:20.0]];
//创建blueView的约束
//设置redView和blueView的高度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
//设置redView和blueView的宽度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
//设置blueView的顶部与redView对齐
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:redView attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0]];
//设置右边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:-20.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeLeading multiplier:1.0 constant:-20.0]];
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换做使用VFL的话，代码如下：
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| NSDictionary *views = NSDictionaryOfVariableBindings(redView, blueView);
CGFloat height = 40;
CGFloat margin = 20;
NSDictionary *metrics = @{ @"margin":@(margin), @"height":@(height) };
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(margin)-[redView]-(margin)-[blueView(==redView)]-(margin)-|" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[redView(==height)]" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[blueView(==redView)]" options:0 metrics:metrics views:views]];
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第四种
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| UIView *redView = [[UIView alloc] init];
redView.translatesAutoresizingMaskIntoConstraints = NO;
redView.backgroundColor = UIColor.redColor;
[self.view addSubview:redView];
UIView *blueView = [[UIView alloc] init];
blueView.translatesAutoresizingMaskIntoConstraints = NO;
blueView.backgroundColor = UIColor.blueColor;
[self.view addSubview:blueView];
UIView *greenView = [[UIView alloc] init];
greenView.translatesAutoresizingMaskIntoConstraints = NO;
greenView.backgroundColor = UIColor.greenColor;
[self.view addSubview:greenView];
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| //创建redView的约束
//设置高度
[redView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:40.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeLeading multiplier:1.0 constant:20.0]];
//设定顶边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:20.0]];
//创建blueView的约束
//设置redView和blueView的高度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
//设置redView和blueView的宽度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
//设置blueView的顶部与redView对齐
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:redView attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:blueView attribute:NSLayoutAttributeLeading multiplier:1.0 constant:-20.0]];
//创建greenView的约束
//设置redView和greenView的高度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:greenView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0.0]];
//设置redView和greenView的宽度相等
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:greenView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
//设置greenView的顶部与redView对齐
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:greenView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:redView attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0]];
//设置右边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:greenView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:-20.0]];
//设置左边距
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:blueView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:greenView attribute:NSLayoutAttributeLeading multiplier:1.0 constant:-20.0]];
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换做使用VFL的话，代码如下：
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| NSDictionary *views = NSDictionaryOfVariableBindings(redView, blueView, greenView);
CGFloat height = 40;
CGFloat margin = 20;
NSDictionary *metrics = @{ @"margin":@(margin), @"height":@(height) };
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(margin)-[redView]-(margin)-[blueView(==redView)]-(margin)-[greenView(==redView)]-(margin)-|" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[redView(==height)]" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[blueView(==redView)]" options:0 metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(margin)-[greenView(==redView)]" options:0 metrics:metrics views:views]];
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