iphone - NSLog 正确显示 NSString - 尝试在标签上显示字符串会使应用程序崩溃（无法识别的选择器）

Question

尝试UILabel使用NSString. NSString在console作品上表现相同。

-(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;
    }
}

控制台输出：

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，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

也许您存储在 self.matchesArray 中的值不是字符串