iOS- UITextField限制输入长度

限制输入长度的问题，在这里完美的解决了！

//先创建一个textField 和 一个button。

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#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 

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#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; }

 只要有基础的，差不多都能看明白。。。