如何比较这个“<null>”字符串？

Question

有时候字符串显示“null”我该怎么检查这个错误？ if（imageUrl ==（id）[NSNull null]） {

}

Answer 1

试试这个。

   if ([imageUrl isKindOfClass:[NSString class]]) {
                  [_profileImageView sd_setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:[UIImage imageNamed:@"PlaceHoldeImage"]];


     }else{
        _profileImageView.image=[UIImage imageNamed:@"PlaceHoldeImage"];


    }

Answer 2

NSString *imageUrl= [ProfileArray valueForKey:@"photo"];

if ([imageUrl isKindOfClass:[NSNull class]])
{
    _profileImageView.image=[UIImage imageNamed:@"PlaceHoldeImage"];
}
else
{                    
    [_profileImageView sd_setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:[UIImage imageNamed:@"PlaceHoldeImage"]];
}
_profileImageView.image=[UIImage imageNamed:@"PlaceHoldeImage"];

Answer 3

使用此代码。它应该肯定有用。

  NSString *imageUrl= [ProfileArray valueForKey:@"photo"];
    if ([imageUrl isKindOfClass:[NSNull class]] ) {
        _profileImageView.image=[UIImage imageNamed:@"PlaceHoldeImage"];
    } else {
        [_profileImageView sd_setImageWithURL:[NSURL URLWithString:imageUrl] placeholderImage:[UIImage imageNamed:@"PlaceHoldeImage"]];
    }

Answer 4

试试这段代码。

NSString *imageUrlString= [photoDict valueForKey:@"photo"];
if (imageUrl.length == 0) 
{
    _profileImageView.image=[UIImage imageNamed:@"PlaceHoldeImage"];
}
else
{
    _profileImageView.image=[UIImage imageNamed:imageUrlString];
}