NSString方法stringByTrimmingCharactersInSet：不修剪逗号

Question

我有以下代码用于从表示数字的某些字符串中删除多余的字符：

NSCharacterSet *charactersToKeep = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
NSCharacterSet *charactersToBeRemoved = [charactersToKeep invertedSet];

NSString *myString = [dictionary objectForKey:@"MyKey"];
myString = [myString stringByTrimmingCharactersInSet:charactersToBeRemoved];
myString = [myString stringByReplacingOccurrencesOfString:@"," withString:@""];

在方法stringByTrimmingCharactersInSet:之后，删除除逗号之外的所有额外字符。调用stringByReplacingOccurencesOfString:后，删除逗号。第一次通话后为什么不删除？

以下是每行代码后myString的示例：

myString = " $9,959 "
myString = "9,959"
myString = "9959"

我也试过

NSCharacterSet *charactersToBeRemoved = [NSCharacterSet decimalDigitCharacterSet];

得到了相同的结果。

Answer 1

stringByTrimmingCharactersInSet：仅修剪字符串末尾的字符，而不是内部字符。