An easy way to create and update AutoLayout Constraints (Mainly to update Width and Height of UIView)
1 - import Category
#import "UIView+UpdateAutoLayoutConstraints.h"
2 - create your UIViews
UIView *myView1 = [[UIView alloc]init];
one.backgroundColor = [UIColor redColor];
one.translatesAutoresizingMaskIntoConstraints = NO; //<<-- Don't forget this line to enable AutoLayout
[self.view addSubview:one];
UIView *myView2 = [[UIView alloc]init];
two.backgroundColor = [UIColor blueColor];
two.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:two];
3 - create initial constraints
NSDictionary *metrics = @{@"height":@50.0};
NSDictionary *views = NSDictionaryOfVariableBindings(myView1,myView2);
[self.view addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat:@"|-[one]-|"
options: 0
metrics:metrics
views:views]];
[self.view addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat:@"V:|-[myView1(50)][myView2]]"
options:NSLayoutFormatAlignAllLeft | NSLayoutFormatAlignAllRight
metrics:metrics
views:views]];
4 - Whenever you want, Update this constraint
//Hide View
[myView1 setConstraintConstant:0 forAttribute:NSLayoutAttributeHeight];
//if constraint doesn't exist, it will be created
[myView1 setConstraintConstant:20 forAttribute:NSLayoutAttributeWidth];
//you can use tools to hide/show a uiview
[myView1 hideByHeight:YES];
//then
[myView1 hideByHeight:NO];