IOS 学习笔记(6) 控件 文本域(UITextField)的使用方法

self.textField.placeholder = @"Please input you userName";

typedef NS_ENUM(NSInteger, UITextFieldViewMode)
{
     UITextFieldViewModeNever,
     UITextFieldViewModeWhileEditing,
     UITextFieldViewModeUnlessEditing,
     UITextFieldViewModeAlways
};

self.textField.clearButtonMode=UITextFieldViewModeAlways;

self.textField.clearsOnBeginEditing = YES;

self.textField.background=[[UIImage imageNamed:@"back.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0.0f, 8.0f, 0.0f, 8.0f)];

UIEdgeINsets UIEdgeInsetsMake(CGFloat top, CGFloat left, CGFloat bottom, CGFloat right);

1 @property (weak, nonatomic) IBOutlet UITextField *txtUserName;
2 @property (weak, nonatomic) IBOutlet UITextField *txtPassword;
3 @property (strong, nonatomic) IBOutlet UIView *contentView;

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.txtUserName.delegate=self;
    self.txtPassword.delegate=self;

    // Do any additional setup after loading the view, typically from a nib.
    //键盘显示消息的回调函数
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShown:) name:UIKeyboardWillShowNotification object:nil];
    
    //键盘隐藏消息的回调函数
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHidden:) name:UIKeyboardWillHideNotification object:nil];
}

#pragma mark-
#pragma mark Keyboard Notification
-(void)keyboardWillShown:(NSNotification *)aNotification
{
    //设置键盘显示的flag
    _keyboardShowing=YES;
    
    //收取消息内容并获得键盘大小
    NSDictionary *info=[aNotification userInfo];
    NSValue *aValue=[info objectForKey:UIKeyboardFrameEndUserInfoKey];
    
    //当设备横屏时，直接取键盘的大小并不准确
    //因为系统为键盘的视图增加了一个stransform的内容
    //所以这里有必要进行一次坐标转换，以保证键盘大小在特定设备方向上的准确
    CGSize keyboardSize = [self.view convertRect:[aValue CGRectValue] fromView:nil].size;
    
    //将键盘大小记录下来
    _sizeKeyboard=CGSizeMake(keyboardSize.width, keyboardSize.height);
    
    //因为要计算UITextField是不是被键盘隐藏了，而键盘时显示在UIWindow上的
    //所以UITextField的坐标也要转换到self.view上，再同一层面上的坐标比较这样才有意义
    CGRect retTextField=[[_activeTextField superview]convertRect:_activeTextField.frame toView:self.view];
    
    //进行移动
    [self moveContentView:self.contentView keyboardSize:_sizeKeyboard textFieldRectOnMainView:retTextField];
}

#pragma mark -
#pragma mark Utility
-(void)moveContentView:(UIView *)aView keyboardSize:(CGSize)sizeKeyboard textFieldRectOnMainView:(CGRect)rectTextField
{
    //UITextField当前是否完全显示出来
    if(CGRectContainsRect(CGRectMake(0.0f, 0.0f, CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame)-sizeKeyboard.height), rectTextField))
    {
        //不需要移动
        return;
    }
    
    //计算需要移动的距离
    //之所以不适用self.view.frame，因为self.view作为程序的根视图
    //所以大小一直是竖屏的大小，横屏时系统只对根视图的transform进行配置，高度不变
    //既然contentView高度不变，只变Y轴起始点，那不如直接取contentView的高度
    float fDelta=sizeKeyboard.height-CGRectGetHeight(aView.frame)+CGRectGetMinY(rectTextField)+CGRectGetHeight(rectTextField);
    
    //移动
    [UIView animateWithDuration:0.3f animations:^{
        aView.frame=CGRectMake(CGRectGetMinX(aView.frame), CGRectGetMinY(aView.frame)-fDelta, CGRectGetWidth(aView.frame), CGRectGetHeight(aView.frame));
    }completion:^(BOOL finished) {
        
    }];
}

-(void)keyboardWillHidden:(NSNotification *)aNotification
{
    //没有焦点中的UITextField了
    _activeTextField=nil;
    
    //设置键盘未显示的flag
    _keyboardShowing=NO;
    
    //将contentView的坐标移动回（0.0，0.0）点
    [UIView animateWithDuration:0.3f animations:^{
        self.contentView.frame=CGRectMake(0.0f, 0.0f, CGRectGetWidth(self.contentView.frame), CGRectGetHeight(self.contentView.frame));
    }completion:^(BOOL finished) {
        
    }];
}

#pragma mark-
#pragma mark UITextField Delegate
//焦点进入UITextField后，可以开始输入的回调函数
-(void)textFieldDidBeginEditing:(UITextField *)textField
{
    //当前焦点的UITextField
    _activeTextField=textField;
    
    //如果没有显示键盘，哪移动的任务交给keyboardWillShown:来做，这里return
    //否则的话，移动的任务在这里完成
    if(!_keyboardShowing)
    {
        return;
    }
    
    //显然，能够走到这里，是因为Next的关系
    //我们要和keyboardWillShown里面写的一样，将有效的UITextField位置取出来
    //检查是否需要移位
    CGRect rectTextField=[[_activeTextField superview]convertRect:_activeTextField.frame toView:self.view];
    
    //contentView的移动必须性检查和执行移动
    [self moveContentView:self.contentView keyboardSize:_sizeKeyboard textFieldRectOnMainView:rectTextField];
}

//点击UITextField对应的键盘的回车键的回调函数
-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    //按了“Next”
    if(textField == self.txtUserName)
    {
        [self.txtPassword becomeFirstResponder];
        return YES;
    }
    
    //按了“Done”
    if(textField == self.txtPassword)
    {
        [self.view endEditing:YES];
        return YES;
    }
    return YES;
}