在NSString中查找字符（＃）的最后一个索引（位置）

Question

想要得到最后一次出现的＃的索引但是下面的代码对另一个角色工作正常，但没有给出特殊性的完美结果“＃”

代码在viewDidLoad中正常工作但在textfield中无法工作shouldChangeCharactersInRange。

代码：

txtTest.text = @"@ashish @test #vijay $4030 @post";


- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
   NSRange range = [textField.text rangeOfString:@"a" options:NSBackwardsSearch];        
    NSLog(@"a :: %d   ",range.location);

    range = [str rangeOfString:@"@" options:NSBackwardsSearch];
    NSLog(@"@ :: %d   ",range.location);

    range = [str rangeOfString:@"#" options:NSBackwardsSearch];
    NSLog(@"# :: %d",range.location);

    range = [str rangeOfString:@"$" options:NSBackwardsSearch];
    NSLog(@"$ :: %d\n",range.location);

}

结果:: a :: 17 @ :: 26 ＃:: 2147483647 $ :: 20

Answer 1

尝试％lu unsigned long而不是％d。工作正常

NSString *str = @"ashish @test #vijay $4030 @post";

NSRange range = [str rangeOfString:@"a" options:NSBackwardsSearch];
NSLog(@"a :: %lu   ",(unsigned long)range.location);

range = [str rangeOfString:@"@" options:NSBackwardsSearch];
NSLog(@"@ :: %lu   ",(unsigned long)range.location);

range = [str rangeOfString:@"#" options:NSBackwardsSearch];
NSLog(@"# :: %lu",(unsigned long)range.location);

range = [str rangeOfString:@"$" options:NSBackwardsSearch];
NSLog(@"$ :: %lu\n",(unsigned long)range.location);

a :: 17

@ :: 26

＃:: 13

$ :: 20

Answer 2

首先，你有拼写错误。它是[HttpGet, Route("GetListBy")] public async Task<IHttpActionResult> GetListBy([FromUri] PaperAdFilterParameter ipaperAdFilterParameter) { var paperAdList = await _paperAdService.GetListAsync(ipaperAdFilterParameter); if (paperAdList.IsNull()) return NotFound(); return Ok(paperAdList); } ，而不是NSString *str。

其余部分在我的机器上运行良好。

NSSting *str

答案：

NSString *str = @"ashish @test #vijay $4030 @post";

NSRange range = [str rangeOfString:@"a" options:NSBackwardsSearch];
NSLog(@"a :: %lu   ",range.location);

range = [str rangeOfString:@"@" options:NSBackwardsSearch];
NSLog(@"@ :: %lu   ",range.location);

range = [str rangeOfString:@"#" options:NSBackwardsSearch];
NSLog(@"# :: %lu",range.location);

range = [str rangeOfString:@"$" options:NSBackwardsSearch];
NSLog(@"$ :: %lu\n",range.location);

你能说得更清楚吗？