获取一个字符串在父字符串中出现次数

太感谢这位大牛啦，原文链接http://ilewen.com/questions/1154

NSUInteger cnt = 0, length = [str length];NSRange range = NSMakeRange(0, length); while(range.location != NSNotFound){  range = [str rangeOfString: @"substr" options:0 range:range];  if(range.location != NSNotFound)  {    range = NSMakeRange(range.location + range.length, length - (range.location + range.length));    cnt++;   }}