How to not allow the user to enter a value more than 190 in uitextfield?

问题

I have to allow values less than 190 in uitextfield while entering itself.we should not allow user to enter 1 to 9 digits after 19.

Can anyone please provide me some info regarding this. I tried the below code.But it's allowing more than 190.

if countElements(textField.text!) + countElements(string) - range.length < 4
{
    var floatValue : Float = NSString(string: toString(textField.text)).floatValue

    return floatValue < 190.0
}

回答1:

How i would do it is set the the uiviewcontroller containing the uitextfield as the delegate of the text field. Then add this:

//If number of characters needs to be less than 190
- (BOOL)textField:(UITextField *)textField 
        shouldChangeCharactersInRange:(NSRange)range 
        replacementString:(NSString *)string 
{
    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    if([newString length]>190){
        return NO;
    }
    return YES;
}

//If value needs to be less than 190
- (BOOL)textField:(UITextField *)textField 
    shouldChangeCharactersInRange:(NSRange)range 
    replacementString:(NSString *)string   
{
    NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    if([newString intValue]>190){
        return NO;
    }
    return YES;
}

回答2:

You can use UITextFieldTextDidChangeNotification and then do the value check in the selector for the notification. Here is an example of implementation I verified in Xcode:

#import "ViewController.h"

@interface ViewController () <UITextFieldDelegate>
@property (strong, nonatomic) IBOutlet UITextField *textField;
@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];
  self.textField.delegate = self;
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldDidChange) name:UITextFieldTextDidChangeNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated {
  [super viewWillDisappear:animated];
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)textFieldDidChange
{
    if ([self.textField.text length] > 3) {
        NSString* subString = [self.textField.text substringWithRange:NSMakeRange(0, 3)];
        self.textField.text = subString;
    }
    if ( [self.textField.text intValue] > 190)
    {
        NSString* subString = [self.textField.text substringWithRange:NSMakeRange(0, 2)];
        self.textField.text = subString;
    }
}

@end

来源：https://stackoverflow.com/questions/27916943/how-to-not-allow-the-user-to-enter-a-value-more-than-190-in-uitextfield

标签

ios

swift

uitextfield