NSString中识别中文字符

UTF8编码：汉字占3个字节，英文字符占1个字节

NSString *text = @"i'm a 苹果。...";
int length = [text length];

for (int i=0; i<length; ++i)
{
NSRange range = NSMakeRange(i, 1);
NSString *subString = [text substringWithRange:range];
const char *cString = [subString UTF8String];
if (strlen(cString) == 3)
{
NSLog(@"汉字:%s", cString);
}
}