Objective C中isEqualToString和operator ==之间的差异是什么？

Question

if(lyricsId == areleased.trackId)

{
  ----------;
  ----------;
}

when i am working with above code it does not entered into that loop So, I used the below code,then it entered into the loop and i got out put.

if([lyricsId isEqualToString:areleased.trackId])
{
    ----------;
    ----------;

}

Is there any difference between == and isEqualToString.

Answer 1

lyricsId and arelease.trackId are (I presume) of type NSString* . The == simply compares the pointers, which will usually be different even if their contents are the same. The isEqualToString method compares their contents.

Answer 2

==将比较指针（地址）的相等性，而isEqualToString:将比较一个字符串是否等于另一个字符串。