如何从 NSURL 末尾删除 3 个字符？

Question

我的第一个问题！我已经能够在不寻求帮助的情况下编写大部分这个 RSS 阅读器（通过通过 stackoverflow 进行大量搜索！）但我在这里被难住了。

 NSString *urlbase = [[NSString alloc] initWithFormat:[links3 objectAtIndex:indexPath.row]];
 [[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlbase]];
 NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet];
 NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];

 NSArray *parts = [urlbase componentsSeparatedByCharactersInSet:whitespaces];
 NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
 urlbase = [filteredArray componentsJoinedByString:@" "];

 NSLog(@"%@ %i" , urlbase, 4353);
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlbase]];

links3 数组是一个带有字符串的NSMutableArray。前几行完美地消除了该数组中每个字符串开头的空间，该数组存储在“urlbase”中，因此它们出来时看起来很好。当我们 NSLog urlbase 时，我们看到：

http://www.feedzilla.com/r/D7E6204FEDBFE541314B997AAB5D2DF9CBA2EFEE

但是，当我们使用：[[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlbase]]

我们看到：http://www.feedzilla.com/r/D7E6204FEDBFE541314B997AAB5D2DF9CBA2EFEE%0A

我该如何解决这个问题？我可以以某种方式删除那些尾部元素吗？谢谢！

工作代码：

    NSMutableArray *links3 = [[NSMutableArray alloc] init];
 RSSAppDelegate *appDelegate = (RSSAppDelegate *)[[UIApplication sharedApplication] delegate];
 links3 = appDelegate.links;
 NSLog(@"%@ %i", [links3 objectAtIndex:indexPath.row], 3453);
 NSString *urlbase = [[NSString alloc] initWithFormat:[links3 objectAtIndex:indexPath.row]];
 [[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlbase]];
 NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet];
 NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];

 NSArray *parts = [urlbase componentsSeparatedByCharactersInSet:whitespaces];
 NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
 urlbase = [filteredArray componentsJoinedByString:@" "];

 NSLog(@"%@ %i" , urlbase, 4353);


 NSLog(@"%@ %i" , urlbase, 345346);
 NSString* fixed = [urlbase stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];

 NSURL *hellothere = [NSURL URLWithString:fixed];
 NSLog(@"%@ %i", hellothere, 54);


    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:fixed]];

嘿，我没说它漂亮。感谢 Diederik Hoogenboom！

Answer 1

试试这个：

[urlbase stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]]

URL 字符串的最后一部分是换行符。