解决这个问题的***的一般方法是使用正则表达式。正则表达式

The best general way to solve this is by using regular expressions. The regular expression

- ？[0-9] * \。？[0-9] *

匹配可选的负号，后跟一些数字，后跟可选的小数点，可选后跟一些其他数字。查看 http://www.regular-expressions.info/floatingpoint.html 关于如何***匹配数字与正则表达式的一个很好的讨论。我在这里给出的正则表达式比页面上显示的更简单，但是有点不太稳健。

matches an optional negative sign, followed by some digits, followed by an optional decimal point, optionally followed by some more digits. Take a look at http://www.regular-expressions.info/floatingpoint.html for a nice discussion on how to best match numbers with a regular expression. The regex I give here is simpler than any shown on that page, but it's somewhat less robust.

要匹配Objective-C中的正则表达式，可以使用NSRegularExpression。它有一个名为enumerateMatchesInString的函数，每当它在字符串中匹配时，它将调用一个代码块。下面是一个如何使用它建立一个NSNumbers数组的例子：

To match regular expressions in Objective-C, you can use an NSRegularExpression. It has a function called enumerateMatchesInString that will call a code block every time it gets a match within a string. Here's an example of how you could use that to build up an array of NSNumbers:

NSString *str = @"<td><font color=#ffffff>35</td>\
<td><font color=#ffffff>0</td>\
<td><font color=#ffffff>0</td>\
<td><font color=#ffffff>0</td>\
<td><font color=#ffffff>1</td>\
<td><font color=#ffffff>2</td>\
<td><font color=#ffffff>0</td>\
<td><font color=#ffffff>1</td>\
<td><font color=#ffffff>16</td>\
<td><font color=#ffffff>45.2</td>\
<td><font color=#ffffff>3.153</td>";
NSMutableArray *numbers = [NSMutableArray new];
NSNumberFormatter *formatter = [NSNumberFormatter new];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"-?[0-9]*\\.?[0-9]*" options:NSRegularExpressionAllowCommentsAndWhitespace error:nil];
[regex enumerateMatchesInString:str options:0 range:NSMakeRange(0, [str length]) usingBlock:^(NSTextCheckingResult *match, NSMatchingFlags flags, BOOL *stop){
    NSString *substr = [str substringWithRange:[match range]];
    NSNumber *number = [formatter numberFromString:substr];
    if (number) {
        [numbers addObject:number];
    }
}];
NSLog(@"ARRAY: %@", numbers);