IOS VFL屏幕自适应

 1 -(void)fun1{  2     //注意使用VFL，不用设置视图的frame
 3     UIView *view = [[UIView alloc] init];  4     view.backgroundColor = [UIColor brownColor];  5  [self.view addSubview:view];  6     
 7     view.translatesAutoresizingMaskIntoConstraints = NO;//注意，要想使约束条件起作用，必须将此属性设置为no
 8     
 9     /*
 10  VFL相关的标识符  11  H:代表水平方向  12  V:代表垂直方向  13  |代表父视图  14  - 代表距离 例（H:|-20-）表示距离父视图左侧20像素  15  []代表子视图相关属性  16      */
 17     
 18     //对子视图View进行约束设置，format表示要设置的约束语句，在本句中意思为：view距离父视图左侧30像素，距离父视图右侧20像素（如果没设置具体的数字，且写了-）  19     //options代表对其方式，默认写0就行  20     //metrics 这里是一个字典，当在format中使用了动态数据比如上现这句:@"H:|-[button(==width)]-|",表示这个button的宽度为width,那么这个参数去哪里找呢？就是在这个字典里面找到key对应的值，如果没有找到这个值，app会crash  21     //views 代表约束条件中所涉及的所有视图（父视图除外）
 22     NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-30-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  23 /*这里用到了一个系统宏定义,NSDictionaryOfVariableBindings(),其作用是生成一个词典,key的名字和对象的标识符相同,以上述为例,生成的词典形式就是{"self.view":self.view,@"_view3":_view3,...},这个词典应当包含需要自动布局的父视图和所有的子视图,  24 */
 25     NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  26     
 27  [self.view addConstraints:arr];  28  [self.view addConstraints:arr1];  29 
 30 }  31 
 32 -(void)fun2{  33     UIView *view = [[UIView alloc] init];  34     view.backgroundColor = [UIColor grayColor];  35  [self.view addSubview:view];  36     
 37     view.translatesAutoresizingMaskIntoConstraints = NO;  38     //[view(>=200)] 表示给view设置尺寸，此时小括号里的关系运算符只能是 == <= >=，注意，改尺寸的值不要与约束冲突，==：约束可以不写，简写成H:[view(==200)] >=：当左右距离只设置了一个或者都未设置，视图的尺寸为最小值，如果两个都设置时，view 的尺寸为屏幕宽度减去左右距离，此时要保证减后的值>=尺寸最小值
 39     
 40     NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view(>=200)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  41     
 42      NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  43  [self.view addConstraints:arr1];  44  [self.view addConstraints:arr];  45     
 46 }  47 
 48 -(void)fun3{  49     UIView *view = [[UIView alloc] init];  50     view.backgroundColor = [UIColor grayColor];  51  [self.view addSubview:view];  52     
 53     view.translatesAutoresizingMaskIntoConstraints = NO;  54     
 55     CGFloat width = 200;  56     
 57     //当我们在设置约束条件时，距离父视图上下左右的像素值以及view的尺寸不是固定的数字(用某个字符串代替)，这时我们需要给metrics设置一个字典，该字典的key必须是约束语句中使用的字符串，对应的value可以自行设置
 58     NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)];  59     
 60     NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  61  [self.view addConstraints:arr1];  62  [self.view addConstraints:arr];  63     
 64 }  65 
 66 -(void)fun4{  67     UIView *view = [[UIView alloc] init];  68     view.backgroundColor = [UIColor grayColor];  69  [self.view addSubview:view];  70     
 71     view.translatesAutoresizingMaskIntoConstraints = NO;  72     
 73     CGFloat width = 200;  74     
 75     //当我们在设置约束条件时，距离父视图上下左右的像素值以及view的尺寸不是固定的数字(用某个字符串代替)，这时我们需要给metrics设置一个字典，该字典的key必须是约束语句中使用的字符串，对应的value可以自行设置
 76     NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)];  77     
 78     NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];  79  [self.view addConstraints:arr1];  80  [self.view addConstraints:arr];  81     
 82     
 83     UIView *view1 = [[UIView alloc] init];  84     view1.backgroundColor = [UIColor purpleColor];  85  [self.view addSubview:view1];  86     
 87     view1.translatesAutoresizingMaskIntoConstraints = NO;  88     
 89     //[view1(view)] 代表view1和view某个方向尺寸相同
 90     NSArray *arr2 = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view1(view)]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view1,view)];  91     
 92     //V:[view]-[view1]-20-|：子视图view1垂直方向距离平级子视图view 8像素（默认）
 93     NSArray *arr3 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[view]-[view1]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view,view1)];  94  [self.view addConstraints:arr2];  95  [self.view addConstraints:arr3];  96     
 97     
 98 }  99 
100 //用VFL实现label自适应
101 -(void)fun5{ 102     UILabel *label = [[UILabel alloc] init]; 103     label.backgroundColor = [UIColor grayColor]; 104     label.numberOfLines = 0; 105     label.lineBreakMode = NSLineBreakByCharWrapping; 106     label.text = @"hiwehfdiuwehdiowqhdoiwehjdoiuwehdiouwhediuwheioudhewiuodhwehoihiuhiuhiuhiluhiuhiuhiuhihuhuuhhuh"; 107  [self.view addSubview:label]; 108     label.translatesAutoresizingMaskIntoConstraints = NO; 109     
110     NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]; 111     
112     NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[label]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]; 113     
114  [self.view addConstraints:arr]; 115  [self.view addConstraints:arr1]; 116 }