Question

我创建了一个从服务器获取数据的方法，一切正常，除非我尝试将字符串设置为例如UILabel或UITextView，没有任何显示和更改！这是我的代码：

    - (void)viewDidLoad
{
    [super viewDidLoad];


    [self getDataFromURL:@"http://somesites.net/panel/services?action=events&num=1"
                setTitle:_eTitle1.text image:_eImage1 description:_eNews1.text];

}

获取数据：

 -(void)getDataFromURL:(NSString*)url setTitle:(NSString*)eTitle
                    image:(UIImageView*)eImages description:(NSString*)eDescriptions {


        NSURL *URL = [NSURL URLWithString:url];
        NSError *error1;
        NSString *strPageContent = [NSString stringWithContentsOfURL:URL encoding:NSUTF8StringEncoding error:&error1];
        strPageContent = [strPageContent gtm_stringByUnescapingFromHTML];
        if ([strPageContent rangeOfString:@"<plist version=\"1.0\">"].location != NSNotFound) {
            NSRange range = [strPageContent rangeOfString:@"<plist version=\"1.0\">"];
            strPageContent = [strPageContent substringWithRange:NSMakeRange(range.location+range.length, strPageContent.length-(range.location+range.length))];
            strPageContent = [strPageContent stringByReplacingOccurrencesOfString:@"</plist>" withString:@""];
        }


        NSError *error = nil;
        NSDictionary *dict = [XMLReader dictionaryForXMLString:strPageContent options:XMLReaderOptionsProcessNamespaces
                                                         error:&error];

        if ([dict count]>0) {

            NSDictionary *dictInner = [dict objectForKey:@"dict"];
            NSArray *arrValues = [dictInner objectForKey:@"string"];



           NSString *  strTitle = [[arrValues objectAtIndex:0] objectForKey:@"text"];
           NSString *strImage = [[arrValues objectAtIndex:1] objectForKey:@"text"];
           NSString *  strDescription = [[arrValues objectAtIndex:2] objectForKey:@"text"];

            eTitle = strTitle;
            eDescriptions = strDescription;

    //        [eImages setImageWithURL:[NSURL URLWithString:strImage]
    //                placeholderImage:[UIImage imageNamed:@"loadingPad.jpg"]];

            NSLog(@"Title: %@ | Image: %@ | Desc: %@",eTitle,strImage,eDescriptions);

        }


    }

编译器给了我正确的信息！但是这些字符串无法设置为我的标签，如果我将我的标签字符串放入其工作的方法中！：

_eTitle1.text = strTitle ;

Answer 1

这是完全正常的：当您将“text”对象传递给方法时，您将指针传递给它。直接为其分配另一个NSString对象将只分配一个新指针。为了对字符串产生副作用，你必须使用NSMutableString，但是UILabel只有一个不可变的NSString用于text属性。因此，唯一的解决方案是传递UILabel或在方法内传递初始化的空可变字符串，通过[eTitleText setString:strTitle]更改内容，然后在方法外部将其分配给UILabel text属性。

所以，要么改变这样的方法（就像你已经做的那样）：

-(void)getDataFromURL:(NSString*)url setTitle:(UILabel*)eTitle
                    image:(UIImageView*)eImages description:(NSString*)eDescriptions {
...
eTitle.text = strTitle;
...

并像这样使用它：

- (void)viewDidLoad
{
    [super viewDidLoad];


    [self getDataFromURL:@"http://somesites.net/panel/services?action=events&num=1"
                setTitle:_eTitle1 image:_eImage1 description:_eNews1.text];

}

或者你可以采取另一种方式：

-(void)getDataFromURL:(NSString*)url setTitle:(NSMutableString*)eTitle
                        image:(UIImageView*)eImages description:(NSString*)eDescriptions
...
[eTitle setString:strTitle];
...

并像这样使用它：

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSMutableString *titleText = [NSMutableString new];
    [self getDataFromURL:@"http://somesites.net/panel/services?action=events&num=1"
                setTitle:titleText image:_eImage1 description:_eNews1.text];
    eTitle1.text = titleText;
}

从自定义方法设置UILabel的文本

1 个答案: