我创建了一个NSMutableAttributedString
,并且我动态地附加了该值。我需要检查此字符串是否为nil
。我手动分配了nil
,但下面的条件仍然失败。有没有办法检查这个?
attribStr = [[NSMutableAttributedString alloc] init];
attribStr = nil;
if([attribStr isEqualToAttributedString:nil]) { // doesn't execute}
答案 0 :(得分:2)
看起来你开始使用Objective-C: - )
当您向nil
发送消息时(通过向isEqualToAttributedString:
发送attribStr
消息,您正在执行此操作),它会立即返回0
。所以你的情况总是错误的。
如果您想检查attribStr
是否为nil
,请执行以下操作:
if (attribStr == nil) {
// ...
}
答案 1 :(得分:1)
简单地:
if (!attribStr) {
// nil
}
答案 2 :(得分:0)
而不是这个
if([attribStr isEqualToAttributedString:nil])
这样做
if(attribStr){
//means attribStr contains non nil value
}else{
//contains nil
}
答案 3 :(得分:0)
Vijay将代码更改为attribStr == nil
NSMutableAttributedString *attribStr = [[NSMutableAttributedString alloc] init];
attribStr = nil;
if(attribStr == nil)
{
NSLog(@"The strig is nil");
}