layout

//    UIView * view = [[ UIView alloc]init];

//    [view setTranslatesAutoresizingMaskIntoConstraints:NO];

//    view.backgroundColor =[UIColor yellowColor];

//    [self.view addSubview:view];

//

//    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[view(160)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]];

//    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[view(160)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]];

//

//

//    UIView * viewa = [UIView new];

//    [viewa setTranslatesAutoresizingMaskIntoConstraints:NO];

//    viewa.backgroundColor =[UIColor redColor];

//    [self.view addSubview:viewa];

//

////    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[viewa(view)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(viewa,view)]];

////

////    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[view]-10-[viewa]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(viewa,view)]];

//

//

//    NSLayoutConstraint * layoutcon = [NSLayoutConstraint constraintWithItem:viewa attribute:NSLayoutAttributeCenterX relatedBy:0 toItem:view attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0.0f];

//    layoutcon.active = YES;

//    NSLayoutConstraint * layouty  = [NSLayoutConstraint constraintWithItem:viewa attribute:NSLayoutAttributeCenterY relatedBy:0 toItem:view attribute:NSLayoutAttributeCenterY multiplier:1.0f constant:0.0f];

//    layouty.active = YES;

//

//    NSLayoutConstraint * layout    =[NSLayoutConstraint constraintWithItem:viewa attribute:NSLayoutAttributeHeight relatedBy:0 toItem:view attribute:NSLayoutAttributeHeight multiplier:0.5f constant:0.0f];

//    layout.active = YES;

//

//    NSLayoutConstraint * layoutw  =[NSLayoutConstraint constraintWithItem:viewa attribute:NSLayoutAttributeWidth relatedBy:0 toItem:view attribute:NSLayoutAttributeWidth multiplier:1.0f constant:0.0f];

//    layoutw.active = YES;

//

//    NSLog(@"%lf",view.bounds.size.width);