Autolayout（VFL）自动适配

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self fun5];
    
}

-(void)fun1{
    //注意使用VFL，不用设置视图的frame
    UIView *view = [[UIView alloc] init];
    view.backgroundColor = [UIColor brownColor];
    [self.view addSubview:view];
    
    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
    
    /*
     VFL相关的标识符
     H:代表水平方向
     V:代表垂直方向
     |代表父视图
     - 代表距离 例（H:|-20-）表示距离父视图左侧20像素
     []代表子视图相关属性
     */
    
    //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-）
    //options代表对其方式，默认写0就行
    //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
    //views 代表约束条件中所涉及的所有视图（父视图除外）
    NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-30-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    
    NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    
    [self.view addConstraints:arr];
    [self.view addConstraints:arr1];

}

-(void)fun2{
    UIView *view = [[UIView alloc] init];
    view.backgroundColor = [UIColor grayColor];
    [self.view addSubview:view];
    
    view.translatesAutoresizingMaskIntoConstraints =  NO;
    //[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
    
    NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view(>=200)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    
     NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    [self.view addConstraints:arr1];
    [self.view addConstraints:arr];
    
}

-(void)fun3{
    UIView *view = [[UIView alloc] init];
    view.backgroundColor = [UIColor grayColor];
    [self.view addSubview:view];
    
    view.translatesAutoresizingMaskIntoConstraints =  NO;
    
    CGFloat width = 200;
    
    //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
    NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)];
    
    NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    [self.view addConstraints:arr1];
    [self.view addConstraints:arr];
    
}

-(void)fun4{
    UIView *view = [[UIView alloc] init];
    view.backgroundColor = [UIColor grayColor];
    [self.view addSubview:view];
    
    view.translatesAutoresizingMaskIntoConstraints =  NO;
    
    CGFloat width = 200;
    
    //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
    NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-left-[view(==width)]" options:0 metrics:@{@"width":[NSNumber numberWithFloat:width],@"left":@30} views:NSDictionaryOfVariableBindings(view)];
    
    NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[view(==100)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)];
    [self.view addConstraints:arr1];
    [self.view addConstraints:arr];
    
    
    UIView *view1 = [[UIView alloc] init];
    view1.backgroundColor = [UIColor purpleColor];
    [self.view addSubview:view1];
    
    view1.translatesAutoresizingMaskIntoConstraints = NO;
    
    //[view1(view)] 代表view1和view某个方向尺寸相同
    NSArray *arr2 = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view1(view)]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view1,view)];
    
    //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）
    NSArray *arr3 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[view]-[view1]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view,view1)];
    [self.view addConstraints:arr2];
    [self.view addConstraints:arr3];
    
    
}

//用VFL实现label自适应
-(void)fun5{
    UILabel *label = [[UILabel alloc] init];
    label.backgroundColor = [UIColor grayColor];
    label.numberOfLines = 0;
    label.lineBreakMode = NSLineBreakByCharWrapping;
    label.text = @"hiwehfdiuwehdiowqhdoiwehjdoiuwehdiouwhediuwheioudhewiuodhwehoihiuhiuhiuhiluhiuhiuhiuhihuhuuhhuh";
    [self.view addSubview:label];
    label.translatesAutoresizingMaskIntoConstraints = NO;
    
    NSArray *arr = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)];
    
    NSArray *arr1 = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[label]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(label)];
    
    [self.view addConstraints:arr];
    [self.view addConstraints:arr1];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end