关于IOS判断字符串长度的方法

 
NSString *text=@"helloworld你好吗";//16
NSUInteger length= text.length;
NSUInteger length2=[text lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSLog(@"length=%lu,length2=%lu,length3=%lu",(unsigned long)length ,(unsigned long)length2,[self unicodeLengthOfString:text]);

-(NSUInteger) unicodeLengthOfString: (NSString *) text {
NSUInteger asciiLength = 0;
for (NSUInteger i = 0; i < text.length; i++) {
unichar uc = [text characterAtIndex: i];
asciiLength += isascii(uc) ? 1 : 2;
}
NSUInteger unicodeLength = asciiLength / 2;
if(asciiLength % 2) {
unicodeLength++;
}
return asciiLength;
}