从NSMutable数组解析/提取和合并字符串

Question

Am trying to figure out how to do this....

I have an NSMutable array populated from an RSS feed as follows :

Item 1 (date, title, description)

Item 2 (date, title, description)

Item 3 (date, title, description)

etc....

What I'm trying to do, is loop through it and create a string for use in an animated ticker as follows :

Item 1 Date - Item 1 Title [a few spaces] Item 2 Date - Item 2 Title [a few spaces] etc.....

I understand how to extract a single element from the array - for example :

NSString *testString1 = [[_parseResults objectAtIndex:0] objectForKey:@"date"];
NSString *testString2 = [[_parseResults objectAtIndex:0] objectForKey:@"title"];

but am stumped as to the best way to loop through the whole thing and construct the combined string - ie Item 1 Date + "-" + Item 1 Title + Item 2 Date + "-" + Item 2 Title etc ?

Answer 1

If you want to loop over them, an easy way might something like this:

NSString* finalStr = nil;
for (int i = 0; i < [_parseResults count]; i++)
{
    NSDictionary* nextItem = [_parseResults objectAtIndex:i];
    NSString* dateStr = [nextItem objectForKey:@"date"]; // You might want to make the keys be named constants
    NSString* titleStr = [nextItem objectForKey:@"title"];
    ...
    finalStr = [finalStr stringByAppendingFormat:@"\t%@-%@", dateStr, titleStr];
}

At the end, finalStr will contain the whole string you want.

Answer 2

You may use fast enumeration, let compiler choose the optimal way to go through your array elements.

for(NSDictionary *rssItem in _parseResults)
{
    NSString* dateString = [rssItem objectForKey:@"date"];
    NSString* titleString = [rssItem objectForKey:@"title"];
    result = [result stringByAppendingFormat:@" %@-%@", dateString, titleString];
}