1 #import "ViewController.h" 2 3 @interface ViewController () 4 5 @end 6 7 @implementation ViewController 8 9 - (void)viewDidLoad { 10 [super viewDidLoad]; 11 12 [self fun5]; 13 14 } 15 16 -(void)fun1{ 17 //注意使用VFL，不用设置视图的frame 18 UIView *view = [[UIView alloc] init]; 19 view.backgroundColor = [UIColor brownColor]; 20 [self.view addSubview:view]; 21 22 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 23 24 /* 25 VFL相关的标识符 26 H:代表水平方向 27 V:代表垂直方向 28 |代表父视图 29 - 代表距离 例（H:|-20-）表示距离父视图左侧20像素 30 []代表子视图相关属性 31 */ 32 33 //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-） 34 //options代表对其方式，默认写0就行 35 //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对就的值，如果没有找到这个值，app会crash 36 //views 代表约束条件中所涉及的所有视图（父视图除外） 37 NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-30-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 38 39 NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 40 41 [self.view addConstraints:arr]; 42 [self.view addConstraints:arr1]; 43 44 } 45 46 -(void)fun2{ 47 UIView *view = [[UIView alloc] init]; 48 view.backgroundColor = [UIColor grayColor]; 49 [self.view addSubview:view]; 50 51 view.translatesAutoresizingMaskIntoConstraints = NO; 52 //[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 53 54 NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view(>=200)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 55 56 NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 57 [self.view addConstraints:arr1]; 58 [self.view addConstraints:arr]; 59 60 } 61 62 -(void)fun3{ 63 UIView *view = [[UIView alloc] init]; 64 view.backgroundColor = [UIColor grayColor]; 65 [self.view addSubview:view]; 66 67 view.translatesAutoresizingMaskIntoConstraints = NO; 68 69 CGFloat width = 200; 70 71 //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 72 NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)]; 73 74 NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 75 [self.view addConstraints:arr1]; 76 [self.view addConstraints:arr]; 77 78 } 79 80 -(void)fun4{ 81 UIView *view = [[UIView alloc] init]; 82 view.backgroundColor = [UIColor grayColor]; 83 [self.view addSubview:view]; 84 85 view.translatesAutoresizingMaskIntoConstraints = NO; 86 87 CGFloat width = 200; 88 89 //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 90 NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)]; 91 92 NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]; 93 [self.view addConstraints:arr1]; 94 [self.view addConstraints:arr]; 95 96 97 UIView *view1 = [[UIView alloc] init]; 98 view1.backgroundColor = [UIColor purpleColor]; 99 [self.view addSubview:view1]; 100 101 view1.translatesAutoresizingMaskIntoConstraints = NO; 102 103 //[view1(view)] 代表view1和view某个方向尺寸相同 104 NSArray *arr2 = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view1(view)]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view1,view)]; 105 106 //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） 107 NSArray *arr3 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[view]-[view1]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view,view1)]; 108 [self.view addConstraints:arr2]; 109 [self.view addConstraints:arr3]; 110 111 112 } 113 114 //用VFL实现label自适应 115 -(void)fun5{ 116 UILabel *label = [[UILabel alloc] init]; 117 label.backgroundColor = [UIColor grayColor]; 118 label.numberOfLines = 0; 119 label.lineBreakMode = NSLineBreakByCharWrapping; 120 label.text = @"hiwehfdiuwehdiowqhdoiwehjdoiuwehdiouwhediuwheioudhewiuodhwehoihiuhiuhiuhiluhiuhiuhiuhihuhuuhhuh"; 121 [self.view addSubview:label]; 122 label.translatesAutoresizingMaskIntoConstraints = NO; 123 124 NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]; 125 126 NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[label]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)]; 127 128 [self.view addConstraints:arr]; 129 [self.view addConstraints:arr1]; 130 } 131 132 - (void)didReceiveMemoryWarning { 133 [super didReceiveMemoryWarning]; 134 // Dispose of any resources that can be recreated. 135 } 136 137 @end