Add subview to UITextView and using autolayout - ios

Question

I have problem with adding subview to UITextView using autoLayout:
in SubTextView : UITextView .m file:
- (instancetype)initWithFrame:(CGRect)frame
{
if(self = [super initWithFrame:frame]) {
_baseline = [[UIView alloc] init];
[self addSubview:_baseline];
[self setBackgroundColor: [UIColor blackColor]];
_baseline.translatesAutoresizingMaskIntoConstraints = NO;
[self setNeedsUpdateConstraints];
}
}
- (void)updateConstraints
{
[super updateConstraints];
NSLayoutConstraint *constraint = nil;
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeTrailing
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeLeading
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeCenterY
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
}
But, this do not work... the self.baseline's frame is always (0, 0, 0, 0)...
Anyone can help?
Edited:
I set a break point at layout subviews, at that time, when layoutSubviews the subviews are inited, and the UITextView is :
<InventoryOverviewListingNameTextView: 0x7fd92b2a1800;
baseClass = UITextView;
frame = (234 36; 399 70.2);
text = '11111111';
clipsToBounds = YES;
gestureRecognizers = <NSArray: 0x7fd92cbd8ca0>;
layer = <CALayer: 0x7fd92cb08900>;
contentOffset: {-0, 10};
contentSize: {399, 70.199997425079346}>
But the frame of the baseline is:
<UIView: 0x7fd92cb90710;
frame = (0 -10; 399 0.5);
layer = <CALayer: 0x7fd92cb907e0>>.
Do not know how to make the y = -10 to y = 69.7.
I feel it is a little like scrollView, to which I solve by add a UIView as contentView on UIScrollView, and UIScrollView itself is added on another UIView. Then I set the contentView's top to scrollView's top, contentView's heigh, and !!!(this is important or autoLayout won't work properly)
contentView's left and right to UIView rather than scrollView.
But I do not see it works for UITextView...
Anyone can help?

Answer 1

The frame will always be (0,0,0,0) because that is the default one that comes whit [[UIView alloc] init].
Have you tried defining the view setting a frame?
- (instancetype)initWithFrame:(CGRect)frame
{
if(self = [super initWithFrame:frame]) {
//Add a frame, does not matter the size
_baseline = [[UIView alloc] initWithFrame:CGRectMake(0,0,20,20)];
//Just to make sure it's there let us give it a color
[_baseline setBackgroundColor:[UIColor green]];
[self addSubview:_baseline];
//Don't run this line just yet.
//[self setNeedsUpdateConstraints];
}
}
If that works, then we found the problem, if it does not, maybe the problem is on the - (void)updateConstraints method.
UPDATE:
So, I sat down and ran your code, I got a few crashes but eventually I managed to make the black box apear inside the text view. I found that the box was not instantiated when the view was looking to layout its subviews, so I tinkered around and here goes, this works, it throws a few constraints warnings but I guess you can work those by yourself.
- (instancetype)initWithFrame:(CGRect)frame
{
if(self = [super initWithFrame:frame]) {
}
return self;
}
-(void)layoutSubviews{
[super layoutSubviews];
if (!_baseline) {
_baseline = [[UIView alloc] init];
[self addSubview:_baseline];
[self setBackgroundColor: [UIColor blackColor]];
[self setNeedsUpdateConstraints];
}
}
- (void)updateConstraints {
[super updateConstraints];
if (_baseline) {
NSLayoutConstraint *constraint = nil;
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeTrailing
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeLeading
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
constraint = [NSLayoutConstraint constraintWithItem:self.baseline
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self
attribute:NSLayoutAttributeCenterY
multiplier:1.f
constant:0.f];
[self addConstraint:constraint];
}
}