小编Zec*_*ang的帖子

NSString *str = nil;
NSLog(@"str = %@",str);
NSLog(@"str.length = %u",str.length);

NSString *str2 = [NSString stringWithFormat:@"%@",str];
NSLog(@"str2 = %@",str2);
NSLog(@"str2.length = %u",str2.length);

NSLog模式是:

str = (null)
str.length = 0
str2 = (null)
str2.length = 6

str2.length = 6让我困惑,为什么？