I'm making in app that includes a user entering the price of an object, and the app outputs the price including tax. However, every time it outputs 0, and I get a run-time error involving the variable, myDouble. I'm trying to take the value put in a text field and multiplying it by 1.06 (I'm starting out with a set tax rate), and then setting a label to the new value. Here is my code:
-(IBAction)textFieldReturn:(id)sender
{
[sender resignFirstResponder];
NSString *myString = inputtext2.text;
double myDouble = [myString doubleValue];
myDouble = myDouble*1.06;
NSLog(#"myDouble: %lf", myDouble);
price.text = [NSString stringWithFormat:#"%g", myDouble];
}
Most likely your inputtext2 variable is nil, so it is returning nothing. If this is an outlet, check the connections in interface builder. If the outlet is not connected, the variable will be nil, so the string value will be nil, so the double value will be 0.
I think you are going to want to use a NSNumberFormatter and check for valid entry.
pseudo code, uncompiled:
-(IBAction)textFieldReturn:(id)sender
{
[sender resignFirstResponder];
NSString *myString = inputtext2.text;
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle: NSNumberFormatterDecimalStyle];
NSNumber *myNumber = [formatter numberFromString: myString];
double myDouble = 0;
if (myNumber != nil) {
myDouble = [myNumber doubleValue];
}
NSString *outputString = [formatter stringFromNumber:myDouble];
price.text = outputString;
}
This should default your number to 0 if the text entered is 0 or not a valid number.
Related
I'm currently pulling info from an sql DB where the 'cachedDist' column is set as a double. However when I pull it into my app and create my array I turn it into an String and the sort will obviously be off, 18.15 will come before 2.15. How do I fix that in my code so it will sort distance as a Double and not a String?
In Bar object.
NSString *cachedDist
#property(nonatomic,copy) NSString *cachedDist;
#synthesize cachedDist;
My while loop in the View Controller.
while (sqlite3_step(sqlStatement)==SQLITE_ROW) {
Bar * bar = [[Bar alloc] init];
bar.barName = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,1)];
bar.barAddress = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,2)];
bar.barCity = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 3)];
bar.barState = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 4)];
bar.barZip = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 5)];
bar.barLat = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 8)];
bar.barLong = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 9)];
if (currentLoc == nil) {
NSLog(#"current location is nil %#", currentLoc);
}else{
CLLocation *barLocation = [[CLLocation alloc] initWithLatitude:[bar.barLat doubleValue] longitude:[bar.barLong doubleValue]];
bar.cachedDist = [NSNumber numberWithDouble:[currentLoc distanceFromLocation: barLocation]/1000];
[thebars addObject:bar];
}
My sorting
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc] initWithKey:#"cachedDist" ascending:YES];
sortedArray = [thebars sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]];
return sortedArray;
NSString has a method doubleValue to make this quite simple:
double cachedDistance = [cachedDistanceString doubleValue];
which you can use in a custom comparator for your sorting, or else make the property an NSNumber or double to make sorting that much easier. (I'm not sure how you are sorting...)
edit:
I re-evaluated your code, and now it looks like we are going from a double to a string to a double... we can cut out the middle-man, so to speak.
In your #prototype section, change the #property:
// #property(nonatomic,copy) NSString *cachedDist; // old way
#property(nonatomic) double cachedDist;
then assign it like this:
bar.cachedDistance = [currentLoc distanceFromLocation: barLocation]/1000;
and remove the lines which create a string from the distance (which is actually just a double).
Alternatively, if you want to be more object oriented, you can (should?) use NSNumber objects:
#property(nonatomic,copy) NSNumber *cachedDist;
...
bar.cachedDistance = [NSNumber numberWithDouble:[currentLoc distanceFromLocation: barLocation]/1000];
Is it possible to predefine constant or variable for an AppleScript in cocoa application?
in other words is the function "addConstantToAppleScript" (used in the following code) definable?
addConstantToAppleScript("myText", "Hello!");
char *src = "display dialog myText";
NSString *scriptSource = [NSString stringWithCString:src];
NSAppleScript *appleScript = [[NSAppleScript alloc] initWithSource:scriptSource];
NSDictionary *scriptError = [[NSDictionary alloc] init];
[appleScript executeAndReturnError:scriptError];
thanks.
If you want to prepend an NSDictionary of key/value pairs to the beginning of an NSString containing AppleScript you could use something like the following function. Personally I would do this as a category on NSString but you have asked for a function.
NSString *addConstantsToAppleScript(NSString *script, NSDictionary *constants) {
NSMutableString *constantsScript = [NSMutableString string];
for(NSString *name in constants) {
[constantsScript appendFormat:#"set %# to \"%#\"\n", name, [constants objectForKey:name]];
}
return [NSString stringWithFormat:#"%#%#", constantsScript, script];
}
This function converts the key/value pairs to AppleScript statements of the form set <key> to "<value>". These statements are then added to the front of the supplied script string. The resulting script string is then returned.
You would use the above function as follows:
// Create a dictionary with two entries:
// myText = Hello\rWorld!
// Foo = Bar
NSDictionary *constants = [[NSDictionary alloc ] initWithObjectsAndKeys:#"Hello\rWorld!", #"myText", #"Bar", #"Foo", nil];
// The AppleScript to have the constants prepended to
NSString *script = #"tell application \"Finder\" to display dialog myText";
// Add the constants to the beginning of the script
NSString *sourceScript = addConstantsToAppleScript(script, constants);
// sourceScript now equals
// set Foo to "Bar"
// set myText to "Hello\rWorld!"
// tell application "Finder" to display dialog myText
NSAppleScript *appleScript = [[NSAppleScript alloc] initWithSource:sourceScript];
New to objective-c and I just can't find the answer to this question anywhere. I'm running a IBAction for a calculation but I need the input from a label to actually equal something else in the equation.
For example:
-(IBAction)calculate; {
float a = 1.05 if ([label1.text] == 1in);
a = 2.07 if ([label1.text] == 2in);
a = 3.07 if ([label1.text] == 3in);
float b = a*([textField1.text floatValue]);
label2.text = [[NSString alloc] initWithFormat:#"%2.f", b];
}
I know I'm not even close to getting it right but I hope you get the idea as to what I'm looking for.
Thank you!
- (void)calculate {
float a;
if ([self.inputField.text isEqualToString:#"1in"]) a = 1.05f;
else if ([self.inputField.text isEqualToString:#"2in"]) a = 2.07f;
else if ([self.inputField.text isEqualToString:#"3in"]) a = 3.07f;
else a = 0.0f;
if (a) {
float b = a * ([self.inputField.text floatValue]);
self.inputField.text = [[NSString alloc] initWithFormat:#"%.2f", b];
}
else self.inputField.text = #"Invalid";
}
- (void)viewDidLoad
{
//...
self.inputField = [[UITextField alloc] initWithFrame:CGRectMake(10.0f, 20.0f, 300.0f, 30.0f)];
[self.inputField setBackgroundColor:[UIColor grayColor]];
[self.view addSubview:self.inputField];
UIButton * doneButton = [[UIButton alloc] initWithFrame:CGRectMake(10.0f, 55.0f, 300.0f, 30.0f)];
[doneButton setBackgroundColor:[UIColor blackColor]];
[doneButton setTitle:#"Done" forState:UIControlStateNormal];
[doneButton addTarget:self action:#selector(calculate) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:doneButton];
[doneButton release];
}
Note: I replaced the output format %2.f to %.2f, cause I guess you may need this format. E.g:
Input > 1in
Output< 1.05
Input > 2in
Output< 4.14
Input > 3in
Output< 9.21
In my Function below if I remove the tempString release statement it works just fine but with it, there is ALWAYS a runtime error. It is a simple function that displays an array in an NSTextField either _stackDisp1 or _stackDisp2 but for some reason releasing the string creates a runtime error Any help?
- (void) displayArr:(NSMutableArray*)stack{
NSTextField *myObj;
if([stack count] <= 10) myObj = _stackDisp1;
else myObj = _stackDisp2;
NSString *tempString = [[NSString alloc]initWithString:#""];
for(NSString *i in stack){
tempString = [NSString stringWithFormat:#"%#\n%#",tempString,i];
}
[myObj setStringValue:tempString];
[tempString release];
}
That's because
tempString = [NSString stringWithFormat:#"%#\n%#",tempString,i];
creates a new autoreleased object assigning it to your variable tempString. The pointer to the first object gets lost and you end up over-releasing an autoreleased object. Just change the initial assignment to
NSString *tempString = #"";
and remove the [tempString release] line.
In the for loop you're assigning tempString to an autoreleased string:
tempString = [NSString stringWithFormat:#"%#\n%#",tempString,i];
releasing it manually results in a BAD_ACCESS.
Also you are probably looking for this:
- (void) displayArr:(NSMutableArray*)stack{
NSTextField *myObj = ([stack count] <= 10) ? _stackDisp1 : _stackDisp2;
[myObj setStringValue:[stack componentsJoinedByString:#"\n"]];
}
The declaration/assignment of myObj was a bit too verbose for my taste,
so I used a ternary operator instead (it's use is not essiential though. Just a matter of style.).
I have an int and for some reason it isn't working after 16 or so. Here's my code:
NSArray *sortedArray;
sortedArray = [doesntContainAnother sortedArrayUsingFunction:firstNumSort context:NULL];
int count2 = [sortedArray count];
//NSLog(#"%d", count2);
int z = 0;
while (z < count2) {
NSString *myString = [sortedArray objectAtIndex:z];
NSString *intstring = [NSString stringWithFormat:#"%d", z];
NSString *stringWithoutSpaces;
stringWithoutSpaces = [[myString stringByReplacingOccurrencesOfString:intstring
withString:#""] mutableCopy];
[hopefulfinal addObject:stringWithoutSpaces];
NSLog(#"%#", [hopefulfinal objectAtIndex:z]);
z++;
}
Edit: It's not the int, it's the stringWithoutSpaces line... I can't figure out what's causing it.
So it (the NSLog, see above the z++) looks like this:
"Here"
"whatever"
"17 whatevere"
"18 this"
etc.
I'm guessing this is related to your earlier question Sort NSArray’s by an int contained in the array, and that you're trying to strip the leading number and whitespace from an array that looks like the one you had in that question:
"0 Here is an object"
"1 What the heck, here's another!"
"2 Let's put 2 here too!"
"3 Let's put this one right here"
"4 Here's another object"
Without know the full input, I'd guess that your code is likely failing because the leading numbers and the value of z are getting out of sync. Since you don't seem to actually care what the leading number is and just want to vamoose it, I'd recommend a different approach that scans for leading digits and extracts the substring from the position where those digits end:
NSArray *array = [NSArray arrayWithObjects:#"1 One",
#"2 Two",
#"5 Five",
#"17 Seventeen",
nil];
NSMutableArray *results = [NSMutableArray array];
NSScanner *scanner;
NSCharacterSet *whitespace = [NSCharacterSet whitespaceCharacterSet];
for (NSString *item in array) {
scanner = [NSScanner scannerWithString:item];
[scanner scanInteger:NULL]; // throwing away the BOOL return value...
// if string does not start with a number,
// the scanLocation will be 0, which is good.
[results addObject:[[item substringFromIndex:[scanner scanLocation]]
stringByTrimmingCharactersInSet:whitespace]];
}
NSLog(#"Resulting array is: %#", results);
// Resulting array is: (
// One,
// Two,
// Five,
// Seventeen
// )
)