字符串中删除指定字符

-(NSString *) stringDeleteString:(NSString *)str
{

NSMutableString *str1 = [NSMutableString stringWithString:str];
for (int i = 0; i < str1.length; i++) {
unichar c = [str1 characterAtIndex:i];
NSRange range = NSMakeRange(i, 1);
if ( c == '-') {  //c 是字符 ，不能用 isEqualToString 这个方法，只能用  == ''   我这里是要把字符串中的“-”删掉
[str1 deleteCharactersInRange:range];
--i;
}
}
NSString *newstr = [NSString stringWithString:str1];
return newstr;
}