I am working on some simple form validation and need some assistance. Basically, I just need to make sure a UITextField doesn't have a '0' or no value whatsoever (nil) when a user runs a simple calculation. If the field does contain either/or a label will be changed to notify the user. Here is my statement:
if ([abc.text isEqualToString:#"0"] || [time.text isEqualToString:nil]) {
self.123.text = #"Please enter a time";
} else { whatever }
Currently the 123 label is outputting NaN if nothing is entered into the abc UITextField.
if (![abc.text isEqualToString:#"0"] &&
![time.text == nil])
{
self.123.text = #"Please enter a time";
}
else
{
whatever
}
Replace [time.text isEqualToString:nil] with [time.text isEqualToString:#""]
You are trying to compare string with a nil object, and since a nil object (nil) is not the same as an empty string (#""), it fails.
Related
I am trying to run through a settings form and make sure that the user hasn't left any of the required fields empty.
Some of the forms fields are secure ( eg password).
Whats the easiest way to loop through all these fields and check they are not empty?
I have tried below - but I get a weird error:
if textfield1.stringValue == "",
textfield2.stringValue == "",
passwordfield.stringValue == "" {
//Shows error: Braced block of statements is an unused closure
}
Additionally I am unable to group all these NSTextfields into an array as the password textfields are NSSecureTextField which despite being inherited from NSTextfield, the are not groupable with NSTextfield.
You can have NSTextField and NSSecureTextField in the same array. This is indeed an easy way to find the empty ones.
let tf = NSTextField()
let stf = NSSecureTextField()
let tf2 = NSTextField()
tf2.stringValue = "some text"
let all = [tf, stf, tf2]
let emptyTextFields = all.filter { $0.stringValue.isEmpty }
Also in your example you can't use commas to group conditions in if, you have to use &&:
if tf.stringValue.isEmpty && stf.stringValue.isEmpty && tf2.stringValue.isEmpty {
// do something
}
but this is not a good solution, better use the array and filter.
Under Swift 2, here's what Eric Aya correctly identified:
if textfield1.stringValue == "" && textfield2.stringValue == "" && == "" {
}
It also compiles under Swift 3.
On the other hand, the code you put in your question actually works in Swift 3.
Other way to check empty string with isEmpty variable of String object.
let userName = ""
let email = ""
if(userName.isEmpty && email.isEmpty) {
print("empty strings")
}
else {
print("good strings")
}
My problem is that I have some text fields that the user enters in numbers, the entered numbers then get saved to the corresponding variable.
However if the user doesn't enter a number and leaves it blank, the text field has a value of 'nil' and so would crash if unwrapped.
So I used an if statement to only unwrap if the contents of the test field are NOT nil, however this doesn't work. My program still unwraps it and crashes because the value is nil...
I don't understand how my if statement is not catching this.
On another note, how do I change my if statement to only allow Int values to be unwrapped and stored, strings or anything else would be ignored.
#IBAction func UpdateSettings() {
if CriticalRaindays.text != nil {
crit_raindays = CriticalRaindays.text.toInt()!
}
if EvapLess.text != nil {
et_raindays_lessthan_11 = EvapLess.text.toInt()!
}
if EvapMore.text != nil {
et_raindays_morethan_11 = EvapMore.text.toInt()!
}
if MaxWaterStorage.text != nil {
max_h2Ostore = MaxWaterStorage.text.toInt()!
}
if CarryForward.text != nil {
carry_forward = CarryForward.text.toInt()!
}
}
Your issue is that while the text exists, it doesn't mean toInt() will return a value.
Say the text was abc, CriticalRaindays.text != nil would be true but CriticalRaindays.text.toInt()! can still be nil, because abc cannot be converted to an Int.
The exact cause of your crash is likely that .text is equal to "", the empty string. It's not nil, but definitely not an Int either.
The better solution is to use optional binding to check the integer conversion and see if that passes, instead of merely the string existing:
if let rainDays = CriticalRaindays.text.toInt() {
crit_raindays = rainDays
}
If that doesn't compile, you possibly need to do Optional chaining:
if let rainDays = CriticalRaindays.text?.toInt()
Not on a Mac atm so can't test it for you but hope this makes sense!
Why not use an if let to unwrap on if the the text field's text is non-nil?
if let textString = self.textField.text as String! {
// do something with textString, we know it contains a value
}
In your ViewDidLoad, set CarryForward.text = "" This way it will never be nil
Edit:
To check if a textfield is empty, you can use this:
if (CarryForward.text.isEmpty) {
value = 10
}
else {
value = CarryForward.text
}
I am Using This code to select my default index title for table in my drop down.
When i run this code on ios 6 it enters in the else part and when i run it on ios 7 it enters in the if part whereas it should enter in the else part.
Please help me on this.
-(void)setSelectedIndexPath:(NSIndexPath *)selectedIndexPath
{
_selectedIndexPath = selectedIndexPath;
if (_selectedIndexPath.row == NSNotFound) {
[self.selectedValueLabel setText:self.title];
}
else{
[self.selectedValueLabel setText:[self.dataSource dropDown:self optionTitleForRowAtIndexPath:_selectedIndexPath]];
}
}
There are few changes in iOS 7 where nil is being used instead of a sentinel value. Set a break point and check if the indexPath is nil for some reason. If it is, [nil row] would return 0 and not NSNotFound.
I m confused with this from many days and couldn't understand how to resolve it.
I get some data from web server and assigning it to string variable.In assigning it if sometimes no data is available then that string is updated to null(NULL) and to nil(nil) sometimes to (null).So I m confused how to compare data in that variable.
if(stringvariable==NULL) // couldnot understand how to compare here ,with NULL or nil or (null)
{
// do something
}
When will the string variable change its state (to NULL or nil or (null)) ?
use this code..
if([stringvariable isEqualToString:#""] || [stringvariable isEqual:nil])
{
//Data not Found
}
else{
// Data not nil
}
You can check like
if([str length]>0 || ![str isEqualToString:#""]) {
// String is not empty
}
It should be :
if(![stringvariable isEqualToString:#""])
{
// stringvariable is not Empty.
}
else
{
// stringvariable is Empty.
}
This is a simple, odd question...
if(tableViewNum == #"One") {
if ([drinkArray objectAtIndex:0] == currentDate) {
[updatedArray addObject:drinkArray];
NSLog(#"MADE THE ELSE1");
}
NSLog(#"MADE THE ELSE2");
}
else if (tableViewNum == #"Two") {
if ([[drinkArray objectAtIndex:0] isEqualToString:yesterdayDate])
[updatedArray addObject:drinkArray];
} else {
NSLog(#"MADE THE ELSE %#",tableViewNum);
[updatedArray addObject:drinkArray];
}
In the very first if statement I ask if tableViewNum == #"One"
But I don't go in that section of the if statement even though tableViewNum actually does equal #"One"
As you can see the very last NSLog all ways comes out as
MADE THE ELSE One
But if tableViewNum really equaled One it would have gone through the if statement not the else statement code...?????
You can't compare strings with the == operator. Use isEqualToString instead:
if([tableViewNum isEqualToString:#"One"]) {
// etc.
… and the same for the rest of the conditions. You're already doing it right in the second block.
To be more specific, you shouldn't compare ANY objects using ==. This compares just the pointers. Use [obj isEqual: otherObj] or with NSStrings isEqualToString: as described above.