浅谈UITextfield的delegate（当然很多时候可用键

本文主要讲述UITextfield的delegate在iOS开发过程中的一些应用

一、到达到textfield在不同输入状态下的不同效果，先看一下实际效果

错误状态.png 正确状态.png 选择状态.png 未填状态.png

下面直接实现

//定义两个属性且要实现代理
@interface LoginViewController()<UITextFieldDelegate>
@property (strong, nonatomic)  UITextField *photoText;
@property (strong, nonatomic)  UITextField *passwordText;

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

当你点击textfield然后又离开则会显示四种状态，打印如下

打印结果.png

//基本布局
//手机号textfield
    self.photoText = [[UITextField alloc]initWithFrame:CGRectMake(100, self.login.y, self.view.width-140, 50)];
     self.photoText.keyboardType = UIKeyboardTypeNumberPad;
    self.photoText.tintColor = [UIColor lightGrayColor];
    self.photoText.placeholder = @"请输入手机号";
    self.photoText.background = [UIImage imageNamed:@"未填"];
    self.photoText.textAlignment = NSTextAlignmentLeft;
    self.photoText.clearButtonMode = UITextFieldViewModeWhileEditing;
    self.photoText.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
    self.photoText.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    [self.view addSubview:self.photoText];
    //密码textfield   
    self.passwordText = [[UITextField alloc]initWithFrame:CGRectMake(100, self.login.y+100, self.view.width-140, 50)];
    self.passwordText.tintColor = [UIColor lightGrayColor];
    self.passwordText.placeholder = @"请输入密码";
    self.passwordText.background = [UIImage imageNamed:@"未填"];
    self.passwordText.textAlignment = NSTextAlignmentLeft;
    self.passwordText.clearButtonMode = UITextFieldViewModeWhileEditing;
    self.passwordText.secureTextEntry = YES;
    [self.view addSubview:self.passwordText];
    self.photoText.delegate = self;
    self.passwordText.delegate = self;

//视图上移的方法
- (void) animateTextField: (UITextField *) textField up: (BOOL) up
{
    //设置视图上移的距离，单位像素，我此间上移20，根据需求自己可变
    const int movementDistance = 20; // tweak as needed
    //三目运算，判定是否需要上移视图或者不变
    int movement = (up ? -movementDistance : movementDistance);
    //设置动画的名字
    [UIView beginAnimations: @"Animation" context: nil];
    //设置动画的开始移动位置
    [UIView setAnimationBeginsFromCurrentState: YES];
    //设置动画的间隔时间
    [UIView setAnimationDuration: 0.20];
    //设置视图移动的位移
    self.view.frame = CGRectOffset(self.view.frame, 0, movement);
    //设置动画结束
    [UIView commitAnimations];
}
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    return YES;
}
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField{
    return YES;
}
- (void)textFieldDidBeginEditing:(UITextField *)textField{
    [self animateTextField: textField up: YES];
    if ([self.photoText isEditing]) {
        self.photoText.background = [UIImage imageNamed:@"选择"];
    }
    if ([self.passwordText isEditing]) {
        self.passwordText.background = [UIImage imageNamed:@"选择"];
    }
}
- (void)textFieldDidEndEditing:(UITextField *)textField{
    [self animateTextField: textField up: NO];
    //判断手机号，此处有正则判断
    if ([YLUtlis checkTelNumber:self.photoText.text]) {
        self.photoText.background = [UIImage imageNamed:@"正确"];
    }
    if (![YLUtlis checkTelNumber:self.photoText.text]){
        self.photoText.background = [UIImage imageNamed:@"错误"];
    }
    if ([self.photoText.text isEqualToString:@""]) {
        self.photoText.background = [UIImage imageNamed:@"未填"];
    }   
    //判断密码，此处有正则判断
    if ([YLUtlis checkPassword:self.passwordText.text] ) {
        self.passwordText.background = [UIImage imageNamed:@"正确"];
    }
    if(![YLUtlis checkPassword:self.passwordText.text] ){
        self.passwordText.background = [UIImage imageNamed:@"错误"];
    }
    if ([self.passwordText.text isEqualToString:@""]) {
        self.passwordText.background = [UIImage imageNamed:@"未填"];
    }    
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
   
    return YES;
}
- (BOOL)textFieldShouldClear:(UITextField *)textField{
    return YES;
}

二、为了能够监听UITextField的值是“成功”变化，来决定保存按钮是否出现（和微信那种成功输入然后button由不可点击到可点击原理类似）

刚进入界面，保存button处于隐藏状态

屏幕快照 2016-07-12 10.48.28.png

成功输入了值或是减少了值（不是点击textfield处于选中状态），出现button

.png

@interface YLUpdataUserNameViewController ()<UITextFieldDelegate>
{
    UITextField *_nameTxtfild;
    UIButton *_saveBtn;
    UILabel *_promptLabel; 
}

@end
@implementation YLUpdataUserNameViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    [self initView];
    self.tabBarController.hidesBottomBarWhenPushed = YES;
    self.title = @"用户昵称";
    _nameTxtfild.delegate = self;
}

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
//string是textfield里面改变的东西，所以只需判断string即可
    if (string!=nil) {
         self.navigationItem.rightBarButtonItem.customView.hidden = NO;
    }
    return YES;
}
- (void)initView
{
    //label
    self.view.backgroundColor = [UIColor whiteColor];
    _nameTxtfild = [[UITextField alloc]initWithFrame:CGRectMake(20, 80, WindowWidth-40, 30)];
    [_nameTxtfild setTextAlignment:NSTextAlignmentLeft];
    [_nameTxtfild setBackground:[UIImage imageNamed:@"userName_textfield"]];//图片是一条线，可更具自己需求   
    _nameTxtfild.text = self.nameString;//（涉及属性传值，此处不赘言）
    [self.view addSubview:_nameTxtfild];
 //提示信息
    _promptLabel = [[UILabel alloc]initWithFrame:CGRectMake(20, 120, WindowWidth-40, 15)];
    _promptLabel.text = @"给自己一个好的名字吧！！！";
    _promptLabel.textColor = [UIColor lightGrayColor];
    _promptLabel.font = [UIFont systemFontOfSize:12.0];
    [self.view addSubview:_promptLabel];
    // 右上加号按钮
    _saveBtn = [UIButton buttonWithType:UIButtonTypeCustom]; 
    [_saveBtn setTitle:@"保存" forState:UIControlStateNormal];
    [_saveBtn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];  
    _saveBtn.titleLabel.font = [UIFont systemFontOfSize:15.f];
    _saveBtn.enabled = NO;
    // 添加监听方法，此处方法省略saveName
    [_saveBtn addTarget:self action:@selector(saveName) forControlEvents:UIControlEventTouchUpInside];
    _saveBtn.size = CGSizeMake(35, 30);
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:_saveBtn];
    [self.navigationItem.rightBarButtonItem setTintColor:[UIColor blueColor]];
    self.navigationItem.rightBarButtonItem.customView.hidden = YES;
}

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