Question

我正在使用UITextField的子类在文本字段的末尾绘制一个“m3”字符串，但有些东西不起作用。我知道这个方法正在调用，因为我已经使用NSLog测试了它，我做错了什么？

我的课程：

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{

    NSString *strM3 = [[NSString alloc] initWithFormat:@" m³"];

    /// Make a copy of the default paragraph style
    NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    /// Set line break mode
    paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;
    /// Set text alignment
    paragraphStyle.alignment = NSTextAlignmentRight;

    NSDictionary *attributes = @{ NSFontAttributeName:[UIFont fontWithName:@"HelveticaNeue-Bold" size:12.0],
                                  NSParagraphStyleAttributeName:paragraphStyle};

    [strM3 drawInRect:rect withAttributes:attributes];

}

Answer 1

UITextField有很多东西在它自己的上面绘制。背景图将被所有这些事情掩盖。要对此进行测试，您可以以编程方式删除所有子视图，并查看是否显示“m3”。

for(UIView *subview in textField.subviews) [subview removeFromSuperview];

我认为您必须设置默认文本，然后在输入新字符时修改输入文本。设置UITextViewDelegate并重载函数shouldChangeCharactersInRange：

- (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange: (NSRange)range replacementString: (NSString *)string {    
  //Do some string manipulation in here to remove the "m3", then add the user's input, then replace the "m3"
}

drawRect方法不是绘图

1 个答案: