UITextField - 输入框

基本属性

    self.testField.font = [UIFont systemFontOfSize:12];
    self.testField.textColor = [UIColor redColor];
    self.testField.borderStyle = UITextBorderStyleNone;
    self.testField.textAlignment = NSTextAlignmentCenter;
    self.testField.backgroundColor = [UIColor yellowColor];
    self.testField.adjustsFontSizeToFitWidth = YES;
    self.testField.minimumFontSize = 8.;

    [self.view endEditing:YES];// 取消编辑，与Field 取消第一响应效果一样，好用！

简单定义

    self.testField.background = [UIImage imageNamed:@""];
    self.testField.disabledBackground = [UIImage imageNamed:@""];
    self.testField.clearsOnBeginEditing = YES;
    self.testField.clearButtonMode = UITextFieldViewModeWhileEditing;
    self.testField.leftViewMode = UITextFieldViewModeAlways;
    self.testField.leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
    // rightView 同理

提示文字

placeholder ：默认的提示文字是与设置输入文字字体一致，颜色深灰色，
attributedPlaceholder：自定义富文本，输入内容也可以使用attributedText
简单举例，具体看Foundation 中的 NSAttributedString 使用。

    self.testField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"test"
                                                                           attributes:@{
                                                                                        NSForegroundColorAttributeName:[UIColor redColor],
                                                                                        NSFontAttributeName:[UIFont systemFontOfSize:22]
                                                                                        }];

代理

没啥好说的。

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    return YES;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    
}

- (BOOL)textFieldShouldEndEditing:(UITextField *)textField{
    return YES;
}

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

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    return YES;
}

- (BOOL)textFieldShouldClear:(UITextField *)textField{
    
    return YES;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField{
    
    return YES;
}

• 比较特殊的 代理

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    NSCharacterSet *cs;
    // return YES 表示可以输入。
    
 
    if ([string isEqualToString:@"\n"])  //按会车可以改变
    {
        return YES;
    }
    
    
    // 控制 长度
    NSString * toBeString = [textField.text stringByReplacingCharactersInRange:range withString:string]; //得到输入框的内容
    if (self.testField == textField) {
        if ([toBeString length] > 20) { //如果输入框内容大于20则弹出警告
            textField.text = [toBeString substringToIndex:20];
            NSLog(@"长度过长");
            return NO;
        }
    }
    
    
    // 控制 内容
    cs = [[NSCharacterSet characterSetWithCharactersInString:@"1234567890\n"]invertedSet];
    NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs]componentsJoinedByString:@""]; //按cs分离出数组,数组按@""分离出字符串
    BOOL canChange = [string isEqualToString:filtered];
    
    
    return canChange;
    
}

通知

UIKIT_EXTERN NSString *const UITextFieldTextDidBeginEditingNotification;
UIKIT_EXTERN NSString *const UITextFieldTextDidEndEditingNotification;
UIKIT_EXTERN NSString *const UITextFieldTextDidChangeNotification;

1 举例，输入变化监听

- (void)addNotification {
    NSNotificationCenter defaultCenter] addObserver:self selector:@selector(testFieldChange:) name:UITextFieldTextDidChangeNotification object:self.testField];
}

- (void)testFieldChange:(NSNotification *)notification {
    NSLog(@"%@",self.testField.text);
}

2 实现上述功能还可以使用 UIControl 类的方法。

        [self.testField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];

3 再其他就是 KVO 方式了。

重绘

修改 输入框的一些位置，等需要重绘，例如输入内容与框下边对齐，而上边空的多，举例：

- (CGRect)editingRectForBounds:(CGRect)bounds {
    // 输入内容 向下偏移 8 px
    return CGRectOffset(bounds, 0, - 8);
}

- (CGRect)textRectForBounds:(CGRect)bounds {
    // 显示内容 向上偏移 8 px
    return CGRectOffset(bounds, 0, 8);
}

其他 更多重绘，更多惊喜。

- (CGRect)borderRectForBounds:(CGRect)bounds;
- (CGRect)textRectForBounds:(CGRect)bounds;
- (CGRect)placeholderRectForBounds:(CGRect)bounds;
- (CGRect)editingRectForBounds:(CGRect)bounds;
- (CGRect)clearButtonRectForBounds:(CGRect)bounds;
- (CGRect)leftViewRectForBounds:(CGRect)bounds;
- (CGRect)rightViewRectForBounds:(CGRect)bounds;

- (void)drawTextInRect:(CGRect)rect;
- (void)drawPlaceholderInRect:(CGRect)rect;