Fixing a few errors, adding support for attributedPlaceholder

This may be an issue due to an oversight in the original code, where I didn't reset `_storedText = @""` in the `else`. I think that would avoid the issue outright. I need to think about it for a bit.

```
    if ([self.text length]) {
        _storedText = [self text];
        if (![_floatLabel alpha]) {
            [self toggleFloatLabel:UIFloatLabelAnimationTypeShow];
        }
    } else {
        if ([_floatLabel alpha]) {
            [self toggleFloatLabel:UIFloatLabelAnimationTypeHide];
        }
        _storedText = nil; // Added this now for the example
    }
```