如何在iPhone SDK中隐含验证码变异

Question

I have a task to work with captcha in my application which gives the same process of verification in my mobile application like website captcha process.

My question is to develop or integrate captcha in my application. and my hole code is developed in native iphone language. I have search a lot for integration of captcha in mobile application. But i haven't find any reference.

So please help me for this to develop captcha in my application without using webview.And provide some code or sample for it.

Answer 1

use this http://iphonesdksnippets.com/post/2009/05/05/Add-text-to-image-%28UIImage%29.aspx find a nice background image for you app, and just randomly generate some number and/or text. not exactly a captcha, but it can work out. Hope it helps!

Answer 2

Though there is no Need to add Captcha in some Application, as Applications are not as like Web, So, as per my thinking there is no Need to attach the Captcha in some Application to prevent the Bots, Still if you need to embed it... Yes, Here is the Possible way, Please check the following codes:

Take these outlets and variables:

NSArray *arrCapElements;
IBOutlet UILabel *Captcha_label;
IBOutlet UITextField *Captcha_field;
IBOutlet UILabel *Status_label;

and IBActions as:

- (IBAction)Reload_Action:(id)sender;
- (IBAction)Submit_Action:(id)sender;

In storyboard choose the font name as Chalkduster 30.0 for the Captcha_label .

Now assign arrCapElements in viewDidLoad() as

arrCapElements = [[NSArray alloc]initWithObjects:@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",@"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"R",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z", nil];

Code for load the Captcha:

-(void)load_captcha{
    @try {
        CGFloat hue = ( arc4random() % 256 / 256.0 );  //  0.0 to 1.0
        CGFloat saturation = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from white
        CGFloat brightness = ( arc4random() % 128 / 256.0 ) + 0.5;  //  0.5 to 1.0, away from black
        Captcha_label.backgroundColor = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
        //Captcha_label.textColor=[UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:1];
        NSUInteger elmt1,elmt2,elmt3,elmt4,elmt5,elmt6;
        elmt1 = arc4random() % [arrCapElements count];
        elmt2= arc4random() % [arrCapElements count];
        elmt3 = arc4random() % [arrCapElements count];
        elmt4 = arc4random() % [arrCapElements count];
        elmt5 = arc4random() % [arrCapElements count];
        elmt6 = arc4random() % [arrCapElements count];

        NSString *Captcha_string = [NSString stringWithFormat:@"%@%@%@%@%@%@",arrCapElements[elmt1-1],arrCapElements[elmt2-1],arrCapElements[elmt3-1],arrCapElements[elmt4-1],arrCapElements[elmt5-1],arrCapElements[elmt6-1]];
        //NSLog(@" Captcha String : %@",Captcha_string);
        Captcha_label.text = Captcha_string;
    }
    @catch (NSException *exception) {
        NSLog(@"%@",exception);
    }
}

Reload Action:

- (IBAction)Reload_Action:(id)sender {

    [self load_captcha];
}

Check the captcha Correct or not:

- (IBAction)Submit_Action:(id)sender {

    NSLog(@"%@ = %@",Captcha_label.text,Captcha_field.text);
    if([Captcha_label.text isEqualToString: Captcha_field.text]){
        [self.view endEditing:YES];
        Status_label.text =@"Success";
        Status_label.textColor = [UIColor greenColor];
    }else{
        Status_label.text =@"Faild";
        Status_label.textColor = [UIColor redColor];
    }
}

It will be shown like this:

Help taken from: Captcha Generator for iOS