iOS UITextField限制输入长度

这篇博客主要讲限制输入长度的问题，前几天有人问我这个问题，说限制长度会出现无法删除问题，于是正好一块发出来给大家看看。textField的缩进，一张背景图片搞定的事，我这里用了leftView纯属附带。

好了废话少说，贴代码，很简单，大家一看便知。

//先创建一个textField 和 一个button。

#import "ViewController.h"



@interface ViewController ()<UITextFieldDelegate> {

    

    UITextField *currentTextFeild;

    UIButton    *touchButton;

}



@end



@implementation ViewController



- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    

    UITextField *textFields = [[UITextField alloc] initWithFrame:CGRectMake(15, 50, self.view.bounds.size.width-15*2, 40)];

    textFields.backgroundColor = [UIColor brownColor];

    textFields.layer.cornerRadius = 5;

    textFields.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 40)];

    textFields.leftViewMode = UITextFieldViewModeAlways;//这两行是为了不让Text太贴textField的左边

    textFields.placeholder = @"请输入手机号";

    textFields.delegate = self;

    [self.view addSubview:textFields];

    currentTextFeild = textFields;

    

    UIButton *enableButton = [UIButton buttonWithType:UIButtonTypeCustom];

    enableButton.frame = CGRectMake(15, 100, self.view.bounds.size.width-15*2, 40);

    enableButton.layer.cornerRadius = 5;

    enableButton.backgroundColor = [UIColor grayColor];

    [enableButton setTitle:@"没内容不可点击" forState:UIControlStateNormal];

    [enableButton setTitle:@"可以按了" forState:UIControlStateSelected];

    [enableButton setTitle:@"按下去了" forState:UIControlStateHighlighted];

    enableButton.enabled = NO;

    [enableButton addTarget:self action:@selector(btnClick) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:enableButton];

    touchButton = enableButton;

}



- (void)btnClick {

    

    

}

//设置textField代理 

#pragma mark -  UITextFieldDelegate

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

    

    return YES;

}



- (void)textFieldDidEndEditing:(UITextField *)textField {

    

    

}



- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    

    //用来判断是否可以继续输入， - range.length是为了判断是否可以删除

    NSInteger currentLength = textField.text.length - range.length + string.length;

    if (currentLength > 11) {

        

        return NO;

    }

    

    //判断按钮是否可以enable = YES

    if (currentTextFeild.text && currentTextFeild.text.length > 0 && currentLength > 0) {

        

        touchButton.enabled = YES;

        touchButton.selected = YES;

    }else {

        

        touchButton.enabled = NO;

        touchButton.selected = NO;

    }

    

    if (currentLength <= 0) {

        

        touchButton.enabled = NO;

        touchButton.selected = NO;

    }

    

    return YES;

}



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

    

    if (currentTextFeild.tag == 11 || currentTextFeild.tag == 12) {

        //手机号

        touchButton.enabled = NO;

        touchButton.selected = NO;;

    }

    

    return YES;

}



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

    

    [textField resignFirstResponder];

    

    return YES;

}

 大家看了代码，差不多就明白了。