按下按钮时如何撤消UITextField？

Question

Im using array on creating an UITextField when i pressed a button. I want to add a new button, Undo function. when i pressed Undo button, the last UITextField I created will be removed.

On my ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UITextFieldDelegate>
{

    NSMutableArray *textfieldform;
    UITextField *textField1;
}

@property (nonatomic) NSInteger text1;

@property (nonatomic, retain) NSMutableArray *textfieldform;
@property (nonatomic, readwrite) int yOrigin;
@property (nonatomic, readwrite) int xOrigin;


-(IBAction) textFieldcreating;
-(IBAction) undo;


@end

On my ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize text1, textfieldform, yOrigin, xOrigin;


- (void)viewDidLoad
{
    [super viewDidLoad];
    //textfieldform = [[NSMutableArray alloc] init];
    // Do any additional setup after loading the view, typically from a nib.
    textfieldform = [NSMutableArray arrayWithCapacity:0];
    yOrigin = 0;
    xOrigin = 10;

}


-(IBAction)textFieldcreating{

    textField1 = [[UITextField alloc] initWithFrame:CGRectMake(xOrigin, yOrigin, 100, 40)];
    textField1.borderStyle = UITextBorderStyleRoundedRect;
    textField1.font = [UIFont systemFontOfSize:15];
    textField1.placeholder = @"enter text";
    textField1.autocorrectionType = UITextAutocorrectionTypeNo;
    textField1.keyboardType = UIKeyboardTypeDefault;
    textField1.returnKeyType = UIReturnKeyDone;
    textField1.clearButtonMode = UITextFieldViewModeWhileEditing;
    textField1.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;    
    textField1.delegate = self;

    [textfieldform addObject:textField1];
    [self.view addSubview:textField1];
    yOrigin = yOrigin + 40 + 10; 
    xOrigin = xOrigin + 20 + 10; 
    //old yorigin + btn height + y offset

}

-(IBAction)undo{
    if ([textfieldform count]>0) {
        [textfieldform removeLastObject];
        [textField1 removeFromSuperview];
    }
}


- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{ 

    NSLog(@"textFieldShouldBeginEditing");
    return YES;
}
- (void)textFieldDidBeginEditing:(UITextField *)textField{           

    NSLog(@"textFieldDidBeginEditing");
    [textField1  setBackgroundColor:[UIColor colorWithRed:(248/255.0) green:(248/255.0) blue:(255/255.0) alpha:1.0]];
    textField1.borderStyle = UITextBorderStyleRoundedRect;
}
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField{

    NSLog(@"textFieldShouldEndEditing");
    textField.backgroundColor = [UIColor clearColor];
    return YES;
}
- (void)textFieldDidEndEditing:(UITextField *)textField{

    NSLog(@"textFieldDidEndEditing");
    [textField1  setBackgroundColor:[UIColor clearColor]];
    textField1.borderStyle = UITextBorderStyleNone;
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    NSLog(@"textField:shouldChangeCharactersInRange:replacementString:");

    if ([string isEqualToString:@"#"]) {
        return NO;
    }
    else {
        return YES;
    }

}
- (BOOL)textFieldShouldClear:(UITextField *)textField{

    NSLog(@"textFieldShouldClear:");
    return YES;
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField{

    NSLog(@"textFieldShouldReturn:");

    if (textField.tag == 1) {
        textField1 = (UITextField *)[self.view viewWithTag:2];
        [textField1 becomeFirstResponder];
    }
    else {
        [textField resignFirstResponder];
    }

    return YES;
}




@end

Answer 1

Give each textfield a tag according the the indexPath where they are located in the array.

-(IBAction)textFieldcreating{

UITextField *textField1 = [[UITextField alloc] initWithFrame:CGRectMake(xOrigin, yOrigin, 100, 40)];
textField1.borderStyle = UITextBorderStyleRoundedRect;
textField1.font = [UIFont systemFontOfSize:15];
textField1.placeholder = @"enter text";
textField1.autocorrectionType = UITextAutocorrectionTypeNo;
textField1.keyboardType = UIKeyboardTypeDefault;
textField1.returnKeyType = UIReturnKeyDone;
textField1.clearButtonMode = UITextFieldViewModeWhileEditing;
textField1.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;    
textField1.delegate = self;

textField1.tag = textfieldform.count;

[textfieldform addObject:textField1];
[self.view addSubview:textField1];
yOrigin = yOrigin + 40 + 10; 
xOrigin = xOrigin + 20 + 10; 
//old yorigin + btn height + y offset

}

Than in your unde action should have something like

-(IBAction)undo{  //Should also check here if you actually have an object at that index path. (for example if there are no text fields created yet)

UITextField *textField = (UITextField *)[self.view viewWithTag:textfieldform.count - 1];
textField = nil;
[textField removeFromSuperview];
[textfieldform removeLastObject];

}

Answer 2

Since you are adding your textFields to an array just get the last object from that array and remove it from its superview.

- (IBAction)undo:(id)sender {
    UITextField *textFieldToRemove = [textfieldform lastObject];
    if (textFieldToRemove) {
        [textfieldform removeObject:textFieldToRemove];
        [textFieldToRemove removeFromSuperview];
    }
}