TextField标记区选择区

在调试UITextField控件的时候，有时候不得不满足各种奇怪(pa)的需求，因此必须了解各种api。只有掌握了足够的api，才能定制出我们想要的效果（满足各种奇葩需求）。

- (void)resetTextWithNoWhite 
{
        NSString * textString = self.text;
        NSRange    markedRang = [self markedRang];
        NSInteger  position   = markedRang.location;
        NSInteger  length     = markedRang.length;
        NSString * markedText = [textString substringWithRange:markedRang];//取出被标记的文字
        textString = [textString stringByReplacingCharactersInRange:markedRang withString:@""];//暂时替换掉被标记的文字
        
        NSRange whiteRang = NSMakeRange(0, 0);
        whiteRang = [textString rangeOfString:@" "];//找出剩下的文字中空格的位置
        while (whiteRang.length > 0) {
            textString = [textString stringByReplacingCharactersInRange:whiteRang withString:@""];
            if (position > whiteRang.location) {
                position = position - whiteRang.length;
            }
            whiteRang = [textString rangeOfString:@" "];
        }
        textString = [textString stringByReplacingCharactersInRange:NSMakeRange(position, 0) withString:markedText];//替换回
        NSLog(@"*******\n markedText:%@ \n position:%ld \n length:%ld \n ******",markedText,(long)position,(long)length);
        if (markedText.length) {
            [UIView performWithoutAnimation:^{
                [self setMarkedText:textString selectedRange:NSMakeRange(position, markedText.length)];//不仅会设置标记区，也会设置选中区，这里textString为整个textField的text
                [self setSelectedRange:NSMakeRange(position + markedText.length, 0)];
            }];
        } else {
            [self setText:textString];
        }
}

//标记区 - 标记区
- (NSRange)markedRang
{
    UITextPosition  * beginning      = self.beginningOfDocument;
    UITextRange     * markedRang     = self.markedTextRange;
    UITextPosition  * markedStart    = markedRang.start;
    UITextPosition  * markedEnd      = markedRang.end;
    const NSInteger location = [self offsetFromPosition:beginning toPosition:markedStart];
    const NSInteger length   = [self offsetFromPosition:markedStart toPosition:markedEnd];
    return NSMakeRange(location, length);
}

//选择区 - 复制的时候选中
- (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];
}