Asked  7 Months ago    Answers:  5   Viewed   70 times

How can I detect any text changes in a textField? The delegate method shouldChangeCharactersInRange works for something, but it did not fulfill my need exactly. Since until it returns YES, the textField texts are not available to other observer methods.

e.g. in my code calculateAndUpdateTextFields did not get the updated text, the user has typed.

Is their any way to get something like textChanged Java event handler.

- (BOOL)textField:(UITextField *)textField 
            shouldChangeCharactersInRange:(NSRange)range 
            replacementString:(NSString *)string 
{
    if (textField.tag == kTextFieldTagSubtotal 
        || textField.tag == kTextFieldTagSubtotalDecimal
        || textField.tag == kTextFieldTagShipping
        || textField.tag == kTextFieldTagShippingDecimal) 
    {
        [self calculateAndUpdateTextFields];

    }

    return YES;
}

 Answers

60

From proper way to do uitextfield text change call back:

I catch the characters sent to a UITextField control something like this:

// Add a "textFieldDidChange" notification method to the text field control.

In Objective-C:

[textField addTarget:self 
              action:@selector(textFieldDidChange:) 
    forControlEvents:UIControlEventEditingChanged];

In Swift:

textField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)

Then in the textFieldDidChange method you can examine the contents of the textField, and reload your table view as needed.

You could use that and put calculateAndUpdateTextFields as your selector.

Tuesday, June 1, 2021
 
Laimoncijus
answered 7 Months ago
99

iOS 8.0 introduces the layoutMargins property on cells AND table views.

This property isn't available on iOS 7.0 so you need to make sure you check before assigning it!

The easy fix is to subclass your cell and override the layout margins property as suggested by @user3570727. However you will lose any system behavior like inheriting margins from the Safe Area so I do not recommend the below solution:

(ObjectiveC)

-(UIEdgeInsets)layoutMargins { 
     return UIEdgeInsetsZero // override any margins inc. safe area
}

(swift 4.2):

override var layoutMargins: UIEdgeInsets { get { return .zero } set { } }

If you don't want to override the property, or need to set it conditionally, keep reading.


In addition to the layoutMargins property, Apple has added a property to your cell that will prevent it from inheriting your Table View's margin settings. When this property is set, your cells are allowed to configure their own margins independently of the table view. Think of it as an override.

This property is called preservesSuperviewLayoutMargins, and setting it to NO will allow the cell's layoutMargin setting to override whatever layoutMargin is set on your TableView. It both saves time (you don't have to modify the Table View's settings), and is more concise. Please refer to Mike Abdullah's answer for a detailed explanation.

NOTE: what follows is a clean implementation for a cell-level margin setting, as expressed in Mike Abdullah's answer. Setting your cell's preservesSuperviewLayoutMargins=NO will ensure that your Table View does not override the cell settings. If you actually want your entire table view to have consistent margins, please adjust your code accordingly.

Setup your cell margins:

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Remove seperator inset
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
           [cell setSeparatorInset:UIEdgeInsetsZero];
    }

    // Prevent the cell from inheriting the Table View's margin settings
    if ([cell respondsToSelector:@selector(setPreservesSuperviewLayoutMargins:)]) {
        [cell setPreservesSuperviewLayoutMargins:NO];
    }

    // Explictly set your cell's layout margins
    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
}

Swift 4:

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    // Remove seperator inset
    if cell.responds(to: #selector(setter: UITableViewCell.separatorInset)) {
        cell.separatorInset = .zero
    }
    // Prevent the cell from inheriting the Table View's margin settings
    if cell.responds(to: #selector(setter: UITableViewCell.preservesSuperviewLayoutMargins)) {
        cell.preservesSuperviewLayoutMargins = false
    }
    // Explictly set your cell's layout margins
    if cell.responds(to: #selector(setter: UITableViewCell.layoutMargins)) {
        cell.layoutMargins = .zero
    }
}

Setting the preservesSuperviewLayoutMargins property on your cell to NO should prevent your table view from overriding your cell margins. In some cases, it seems to not function properly.

If all fails, you may brute-force your Table View margins:

-(void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    // Force your tableview margins (this may be a bad idea)
    if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
        [self.tableView setSeparatorInset:UIEdgeInsetsZero];
    }

    if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {
        [self.tableView setLayoutMargins:UIEdgeInsetsZero];
    }
} 

Swift 4:

func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    // Force your tableview margins (this may be a bad idea)
    if tableView.responds(to: #selector(setter: UITableView.separatorInset)) {
        tableView.separatorInset = .zero
    }
    if tableView.responds(to: #selector(setter: UITableView.layoutMargins)) {
        tableView.layoutMargins = .zero
    }
}

...and there you go! This should work on iOS 7 and 8.


EDIT: Mohamed Saleh brought to my attention a possible change in iOS 9. You may need to set the Table View's cellLayoutMarginsFollowReadableWidth to NO if you want to customize insets or margins. Your mileage may vary, this is not documented very well.

This property only exists in iOS 9 so be sure to check before setting.

if([myTableView respondsToSelector:@selector(setCellLayoutMarginsFollowReadableWidth:)])
{
    myTableView.cellLayoutMarginsFollowReadableWidth = NO;
} 

Swift 4:

if myTableView.responds(to: #selector(setter: self.cellLayoutMarginsFollowReadableWidth)) {
    myTableView.cellLayoutMarginsFollowReadableWidth = false
}

(above code from iOS 8 UITableView separator inset 0 not working)

EDIT: Here's a pure Interface Builder approach:

TableViewAttributesInspector TableViewCellSizeInspector

NOTE: iOS 11 changes & simplifies much of this behavior, an update will be forthcoming...

Tuesday, June 1, 2021
 
KHM
answered 7 Months ago
KHM
47

I would get the JTextArea's Document via getDocument() (a PlainDocument actually) and use a DocumentListener to listen for changes. This way you'd capture changes from key strokes and also from copy/paste/cut events.

Sunday, July 4, 2021
 
PandemoniumSyndicate
answered 6 Months ago
76

Binding to both events is the typical way to do it. You can also bind to the paste event.

You can bind to multiple events like this:

$("#textbox").on('change keyup paste', function() {
    console.log('I am pretty sure the text box changed');
});

If you wanted to be pedantic about it, you should also bind to mouseup to cater for dragging text around, and add a lastValue variable to ensure that the text actually did change:

var lastValue = '';
$("#textbox").on('change keyup paste mouseup', function() {
    if ($(this).val() != lastValue) {
        lastValue = $(this).val();
        console.log('The text box really changed this time');
    }
});

And if you want to be super duper pedantic then you should use an interval timer to cater for auto fill, plugins, etc:

var lastValue = '';
setInterval(function() {
    if ($("#textbox").val() != lastValue) {
        lastValue = $("#textbox").val();
        console.log('I am definitely sure the text box realy realy changed this time');
    }
}, 500);
Friday, July 9, 2021
 
VitaCoco
answered 5 Months ago
81

No you can not read or save fingerprint data. Even Apple does not collect this data. You can only use the Touch ID sensor to unlock your app with the fingerprints the user has already saved in the system preferences.

Saturday, August 21, 2021
 
c0m4
answered 4 Months ago
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