I have programatically set an image to a UIViewController background. How can i add autolayout programatically so it gets displayed both in iPad and iPhone?
The code is below:
UIImageView *bkImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"bkImage.png"]];
[self.view addSubview:bkImage];
1) Create the necessary constraint using one of the NSLayoutConstraint class methods that give you a constraint.
2) Add it to the view using the UIview's methods for adding a constraint.
This adds constraints of 0 leading, 0 trailing, 0 top and 0 bottom. You can modify them as per your needs.
[bkImage setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bkImage
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTrailing
multiplier:1.0f
constant:0.0f]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bkImage
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeading
multiplier:1.0f
constant:0.0f]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bkImage
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTop
multiplier:1.0f
constant:0.0f]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bkImage
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0f
constant:0.0f]];
Related
I have a view called profile which is taking (0,0,320,60) size in storyboard which is taking full width but 60 height, and i am trying to place another view called ranking inside it at the center and what ever the device is iPhone4s,5s,6s,6 it should just take my view and put it at the center.
Here is what i tried:
ranking.frame = CGRectMake(0, 0, 120, 60);
ranking.center = self.Profile.center;
The current code is not centering my view In all devices. what can i do to do it dynamically ?
You can use AutoLayout with the following method:
+ (void)centerView:(UIView *)view inContainerView:(UIView *)containerView withSuperView:(UIView *)superView
{
[superView addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:containerView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[superView addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:containerView attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0]];
}
You can add the method above in your ViewController or in a helper class.
Remember to set the translatesAutoresizingMaskIntoConstraints property to false before using AutoLayout on your view.
So if ranking is your subview and self.Profile is your superView you can do the following.
UIView *ranking = [[UIView alloc] init];
ranking.translatesAutoresizingMaskIntoConstraints = false;
[self.Profile addSubview:ranking];
[[self class] centerView:ranking inContainerView:self.Profile withSuperView:self.Profile];
[self.Profile addConstraint:[NSLayoutConstraint constraintWithItem:ranking attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:120]];
[self.Profile addConstraint:[NSLayoutConstraint constraintWithItem:ranking attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:60]];
In my application I have inserted UIViews on view controller. My main requirement is that I want to set equal widths for both UIViews using auto-layouts "Constraint with item format".
For this I have written some code but I did not get equal widths. What did I do here wrong?
I want get result like below image (i.e need to set equal widths for both UIViews).
My code:
#import "ViewController8.h"
#interface ViewController8 ()
{
UIView * myView1;
UIView * myView2;
}
#end
#implementation ViewController8
- (void)viewDidLoad {
[super viewDidLoad];
myView1 = [[UIView alloc] init];
myView1.backgroundColor = [UIColor lightGrayColor];
myView1.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:myView1];
myView2 = [[UIView alloc] init];
myView2.backgroundColor = [UIColor redColor];
myView2.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:myView2];
[self operation2];
}
-(void)operation2
{
//Applying autolayouts for myview2
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView2
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:0
multiplier:1.0
constant:50]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView2
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:-10]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView2
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:-30]];
//Applying autolayouts for myview1
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:10]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:0
multiplier:1.0
constant:50]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:myView2
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:-30]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:-30]];
}
Equal width constraint is not there in your posted code. Try adding this
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:nil
attribute:NSLayoutAttributeNotAnAttribute
multiplier:1.0
constant:200]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:myView2
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:myView1
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0]];
It's enough to add the equal-width constraint
[NSLayoutConstraint constraintWithItem:myView1
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:myView2
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0];
You must not define the width of the two views explicitly using constraints because view1 is pinned to the leading edge of the superview, view2 is pinned to the trailing edge of the superview and the trailing edge of view1 is pinned to the leading edge of view2. Hence, the constraint system is fully determined after adding the above equal-width constraint.
This is what adding the constraint will lead to:
Contemporary solution is using NSLayoutAnchor
myView1.widthAnchor.constraint(equalTo: myView2.widthAnchor)
don't forget to activate this using isActive = true, or via NSLayoutConstraint.activate().
How to add constraint for subview of view controller
explain briefly
// create a new view
self.containerView = [UIView new];
// before adding constraints always add respective view to superview
[self.view addSubview:self.containerView];
[self.containerView setTranslatesAutoresizingMaskIntoConstraints:false];
// add container on newly added view
NSLayoutConstraint *topConstraintContainer = [NSLayoutConstraint constraintWithItem:self.containerView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.topLayoutGuide attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
NSLayoutConstraint *leadingConstraintContainer = [NSLayoutConstraint constraintWithItem:self.containerView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.containerView.superview attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0];
NSLayoutConstraint *trailingConstraintContainer = [NSLayoutConstraint constraintWithItem:self.containerView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.containerView.superview attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:0];
NSLayoutConstraint *bottomConstraintContainer = [NSLayoutConstraint constraintWithItem:self.containerView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.bottomLayoutGuide attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0];
// add constraint to superview of respective view
[self.view addConstraints:#[topConstraintContainer,leadingConstraintContainer,trailingConstraintContainer,bottomConstraintContainer]];
There are alot of possibilities, but this is the main flow
Also there are third party libraries available which makes adding constraints easier, like
PureLayout
From the starting till the end, how do I initialise an UIImageView programmatically, and constraint the frame to the middle of the screen so that when the devices with different width is used, it is still in the middle.
Another words, how do I autolayout my outlets programmatically? With constraints?
For example, my background image is required to be in full screen, with constraining all the sides with constant 0. What is tthe coding basically from the start until the end?
Hope this helps you
{
UIView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"your_image"]];
imageView.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:imageView];
[imageView addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:1 constant:YOUR_HEIGHT_CONSTANT]];
[imageView addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:1 constant:YOUR_WIDTH_CONSTANT]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1 constant:0]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:imageView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:0]];
[self.view addSubview:imageView];
}
I'm trying to add a UISlider to my view programmatically including constraints so that its width adapts to the whole screen width.
This is what I got so far:
//2 Add UISlider
self.slider = [[UISlider alloc] init];
[self.view addSubview:self.slider];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.slider
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeft
multiplier:1
constant:0]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.slider
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeRight
multiplier:1
constant:0]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.slider
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1
constant:0]];
Missing self.slider.translatesAutoresizingMaskIntoConstraints = NO; Your code is working fine for me. See the below image