UITextField 光标位置，禁止输入编辑，限制输入小数点位数

1.设置placeholder颜色

[textField setValue:[UIColor greenColor] forKeyPath:@"_placeholderLabel.textColor"];

2.设置光标颜色

textField.tintColor= [UIColor greenColor];

3.设置获取光标位置

- (NSRange)selectedRange {
    UITextPosition* beginning = self.beginningOfDocument;
    UITextRange* selectedRange = self.selectedTextRange;
    UITextPosition* selectionStart = selectedRange.start;
    UITextPosition* selectionEnd = selectedRange.end;
    const NSInteger location = [self offsetFromPosition:beginning toPosition:selectionStart];
    const NSInteger length = [self offsetFromPosition:selectionStart toPosition:selectionEnd];
    return NSMakeRange(location, length);
}

- (void)setSelectedRange:(NSRange)range  {// 备注：UITextField必须为第一响应者才有效
    UITextPosition* beginning = self.beginningOfDocument;
    UITextPosition* startPosition = [self positionFromPosition:beginning offset:range.location];
    UITextPosition* endPosition = [self positionFromPosition:beginning offset:range.location + range.length];
    UITextRange* selectionRange = [self textRangeFromPosition:startPosition toPosition:endPosition];
    [self setSelectedTextRange:selectionRange];
}

4.禁止输入编辑

//第1种方法
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    if (action == @selector(paste:))//禁止粘贴
        return NO;
    if (action == @selector(select:))// 禁止选择
        return NO;
    if (action == @selector(selectAll:))// 禁止全选
        return NO;
    return [super canPerformAction:action withSender:sender];
}
//第2种方法
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
    UIMenuController *menuController = [UIMenuController sharedMenuController];
    if (menuController) {
        [UIMenuController sharedMenuController].menuVisible = NO;
    }
    return NO;
}

5.监听数值变化的三种方法

#pragma mark - 直接添加监听方法
-(void)addTargetMethod{
    [self.textField addTarget:self action:@selector(textFieldTextChange:) forControlEvents:UIControlEventEditingChanged];
}
-(void)textFieldTextChange:(UITextField*)textField{
    NSLog(@"textField - 输入框内容改变,当前内容为: %@",textField.text);
}
#pragma mark - NSNotificationCenter 添加监听方法
-(void)addNSNotificationCenter{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFieldTextNotificationChange:) name:UITextFieldTextDidChangeNotification object:self.textField];
}
-(void)textFieldTextNotificationChange:(NSNotification*)noti{
    UITextField*currentTextField = (UITextField*)noti.object;
    NSLog(@"textField - 输入框内容改变,当前内容为: %@",currentTextField.text);
}
#pragma mark - kvo 监听方法
-(void)addKVO{
    [self.textField addObserver:self forKeyPath:@"text" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];
    self.textField.text=@"123";
}
-(void)observeValueForKeyPath:(NSString*)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void*)context{
    if([keyPathisEqualToString:@"text"] && object ==self.textField) {
        NSLog(@"textField - 输入框内容改变,当前内容为: %@",self.textField.text);
    }else{
        [superobserveValueForKeyPath:keyPathofObject:objectchange:changecontext:context];
    }
}

6.限制只能输入小数点后一位，并且限制大小

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if (textField == self.textField) {
        //如果输入的是"."  判断之前已经有"."或者字符串为空
        if ([string isEqualToString:@"."] && ([textField.text rangeOfString:@"."].location != NSNotFound || [textField.text isEqualToString:@""])) {
            return NO;
        }
        //拼出输入完成的str,判断str的长度大于等于"."的位置）
        NSMutableString *str = [[NSMutableString alloc] initWithString:textField.text];
        [str insertString:string atIndex:range.location];
        if (str.length >= [str rangeOfString:@"."].location + 3){
            return NO;
        }
        // 涉及到字符转转小数的一定要 doubleValue  floatValue转的值不准确
        CGFloat inputValue = str.doubleValue;
        if (inputValue > 100) {
            return NO;
        }
    }
    return YES;
}