目标C：检查字符串的开头

NSString *string1 = @\"Hello World\";

 if (string1 startwith \"Hello\")

if ([string1 hasPrefix:@\"Hello\"])

NSRange aRange = [myString rangeOfString:@\"Hello\"];
if (aRange.location ==NSNotFound) {
  NSLog(@\"string not found\");
} else {
  NSLog(@\"string was at index %d \",aRange.location);
}