Question

尝试使用UILabel更新NSString时，应用崩溃了。在NSString上显示相同的console。

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if (self.connectionData)
    {
        NSError *error;
        self.dict = [NSJSONSerialization JSONObjectWithData:self.connectionData options:kNilOptions error:&error];
        self.matchesArray = self.dict[@"matches"];

        NSString *title = [self.matchesArray valueForKey:@"title"];
        NSLog(@"NSString TITLE contains: %@", title);
        self.titleLabel.text = title;
    }
}

CONSOLE OUTPUT：

2013-01-16 13:54:08.550 ZEITreisen[3168:c07] NSString TITLE contains: (
    "Mark und Dollar"
)
2013-01-16 13:54:08.552 ZEITreisen[3168:c07] -[__NSArrayI isEqualToString:]: unrecognized selector sent to instance 0xde93850
(lldb)

Answer 1

title不是NSString，而是NSArray

所以

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if (self.connectionData)
    {
        NSError *error;
        self.dict = [NSJSONSerialization JSONObjectWithData:self.connectionData options:kNilOptions error:&error];
        self.matchesArray = self.dict[@"matches"];

        NSArray *title = [self.matchesArray valueForKey:@"title"];
        NSLog(@"NSString TITLE contains: %@", title);
        self.titleLabel.text = [title lastObject];
    }
}

Answer 2

尝试：

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if (self.connectionData)
    {
        NSError *error;
        self.dict = [NSJSONSerialization JSONObjectWithData:self.connectionData options:kNilOptions error:&error];
        self.matchesArray = self.dict[@"matches"];

        NSString *title = [self.matchesArray valueForKey:@"title"];
        NSLog(@"NSString TITLE contains: %@", title);
        self.titleLabel.text = [NSString stringWithFormat:@"%@",[title objectAtIndex:0]];
    }
}

Answer 3

您存储在self.matchesArray中的值可能不是字符串

NSLog正确显示NSString - 试图在标签上显示字符串会导致应用程序崩溃（无法识别的选择器）

3 个答案: