I'm making my first iOS app. I simply want to multiply the value from pressureField with temperatureField. I used a helloiPhone.app to get things going. So everything is working if I use one field, but I don't know how to set the value of h to two multiplied vars.
Here's what my mainview.m looks like:
- (void) sayHello: (id) sender {
h = 23;
helloLabel.text =
[NSString stringWithFormat: @"%.2f", h];
[pressureField resignFirstResponder];
[tempField resignFirstResponder];
tempFiel开发者_高级运维d.text = @"";
pressureField.text = @"";
}
I'm NEW to Objective C...so be easy on me. I'm just hobbying. :)
If you're talking about how to get the values and convert them to a numeric format, then something like the following should do the trick...
// Grab the values from the UITextFields.
float pressureValue = [[pressureField text] floatValue];
float temperatureValue = [[temperatureField text] floatValue];
// Multiply them.
float h = pressureValue * temperatureValue;
You should be able to simply replace your initial h = 23;
line with the above. (That said, I've not checked the above in a compiler, but it's pretty simple so it should be OK.) :-)
What you're doing here is getting the textual value from the UITextFields (that you've presumably set up as IBOutlets in your interface file), which are supplied as a NSString pointer via the UITextField text
method. We're then using the NSString floatValue
method to obtain the value in a suitable numeric format.
Incidentally, I'd really recommend a good read of Apple's class reference documentation (such as the UITextField & NSString docs linked above) - it's very good quality and you'll learn a lot from simply looking at some of the available methods.
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