Extracting string from a string in Objective-C

Question

I'm trying to extract part of a GData supplied string for the YouTube API. I can separate out the video Title and Thumbnail strings but need to create a Text description label. I have copied the full string below but the difficulty I am having is extracting the following part from this.

I'm stuck on how to create a new NSString by finding type:plain content copying the text that follows and then ending the new string on the } delimiter.

{type:plain content:I made a video pretty much every day for a whole week, and now I'm not feeling quite as stressed out as I was previously. The end!

Hank (and his brother John): http://youtube.com/vlogbrothers}

I have tried using a scanner without success and any advice or pointers on this problem would be appreciated.

The full format of the full string is below.

GDataEntryYouTubeVideo 0xc125e20: {v:2.1 title:Crisis Averted contentSrc:https://www.youtube.com/v/RKQWfVzUBt8?version=3&f=user_uploads&app=youtube_gdata etag:W/"DUEGR347eCp7I2A9WhVVEEo." authors:1 categories:12 links:alternate,video.responses,video.related,mobile,self id:tag:youtube.com,2008:video:RKQWfVzUBt8 rating:+19935/-228 comment:GDataComment 0xc12c260: {feedLink:GDataFeedLink 0xc12c9c0: {href:https://gdata.youtube.com/feeds/api/videos/RKQWfVzUBt8/comments rel:http://gdata.youtube.com/schemas/2007#comments countHint:7096 href:https://gdata.youtube.com/feeds/api/videos/RKQWfVzUBt8/comments countHint:7096 rel:http://gdata.youtube.com/schemas/2007#comments}} stats:GDataYouTubeStatistics 0xc12d640: {viewCount:810340 favoriteCount:1096} mediaGroup:GDataYouTubeMediaGroup 0xc12e700: {categories:(
    "GDataMediaCategory 0xc131ab0: {label:People & Blogs scheme:http://gdata.youtube.com/schemas/2007/categories.cat content:People}" ) contents:(
    "GDataMediaContent 0xc130750: {url:https://www.youtube.com/v/RKQWfVzUBt8?version=3&f=user_uploads&app=youtube_gdata type:application/x-shockwave-flash medium:video isDefault:true expression:full duration:201}",
    "GDataMediaContent 0xc130f80: {url:rtsp://v5.cache2.c.youtube.com/CigLENy73wIaHwnfBtRcfRakRBMYDSANFEgGUgx1c2VyX3VwbG9hZHMM/0/0/0/video.3gp type:video/3gpp medium:video expression:full duration:201}",
    "GDataMediaContent 0xc131530: {url:rtsp://v2.cache2.c.youtube.com/CigLENy73wIaHwnfBtRcfRakRBMYESARFEgGUgx1c2VyX3VwbG9hZHMM/0/0/0/video.3gp type:video/3gpp medium:video expression:full duration:201}" ) credits:(
    "GDataMediaCredit 0xc131ff0: {role:uploader scheme:urn:youtube content:charlieissocoollike unparsedAttr:yt:display}" ) thumbnails:(
    "GDataMediaThumbnail 0xc132c10: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/default.jpg height:90 width:120 time:00:01:40.500}",
    "GDataMediaThumbnail 0xc1336e0: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/mqdefault.jpg height:180 width:320}",
    "GDataMediaThumbnail 0xc133bb0: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/hqdefault.jpg height:360 width:480}",
    "GDataMediaThumbnail 0xc133f40: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/1.jpg height:90 width:120 time:00:00:50.250}",
    "GDataMediaThumbnail 0xc134320: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/2.jpg height:90 width:120 time:00:01:40.500}",
    "GDataMediaThumbnail 0xc134630: {url:http://i.ytimg.com/vi/RKQWfVzUBt8/3.jpg height:90 width:120 time:00:02:30.750}" ) keywords:GDataMediaKeywords 0xc134b70: {content:Charlie McDonnell, charlieissocoollike, YouTube, Mid-Life, Crisis, Week, Averted, Hank Green, vlogbrothers, America keywords:Charlie McDonnell, charlieissocoollike, YouTube, Mid-Life, Crisis, Week, Averted, Hank Green, vlogbrothers, America} description:GDataMediaDescription 0xc132880: {type:plain content:I made a video pretty much every day for a whole week, and now I'm not feeling quite as stressed out as I was previously. The end!

Hank (and his brother John): http://youtube.com/vlogbrothers} players:(
    "GDataMediaPlayer 0xc130960: {url:https://www.youtube.com/watch?v=RKQWfVzUBt8&feature=youtube_gdata_player}"

score 0 · Answer 1 · answered May 03 '12 at 20:57

0

That looks like JSON, if you are targeting iOS5 only you could use the built in JSON converter to convert that JSON into an NSDictionary, where you can easily find the data you are looking for.

answered May 03 '12 at 20:57

Kendall Helmstetter Gelner

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Alladinian · Answer 2 · 2012-05-03T22:10:55.167

0

Your string may seem like JSON but its not valid JSON. One way to accomplish what you ask is by using a regular expression (iOS4+). You could try something like this (assuming that myString is an NSString with the text you have provided...):

NSError *error;
NSRegularExpression *regex = [NSRegularExpression 
                              regularExpressionWithPattern:@"\\{type:plain.+\\}(?=\\s)"
                              options:NSRegularExpressionDotMatchesLineSeparators
                              error:&error];

NSRange range   = [regex rangeOfFirstMatchInString:myString
                                           options:0 
                                             range:NSMakeRange(0, [myString length])];
NSString *result = [myString substringWithRange:range];

result now is:

{type:plain content:I made a video pretty much every day for a whole week, and now I'm not feeling quite as stressed out as I was previously. The end!

Hank (and his brother John): http://youtube.com/vlogbrothers}

I am not suggesting that this is the best way to do this and I agree that if you could have a valid JSON string, deserialization (as Kendall suggested) would be optimal. But at least is something that could do the job...

edited May 03 '12 at 22:10

answered May 03 '12 at 21:59

Alladinian

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Thanks. The Regex example you gave doesn't quite extract what I need (characters at the beginning and end) but i will research this in order to fettle it in to shape. – Tim Gibson May 04 '12 at 13:37
But I think I am going about this in the wrong way. What I feel would be better is to extract the content text directly from the GData feed but again, having trawled through GDataTextConstruct, GDataAtomContent etc... in the GData API, still at a loss on how to do this. – Tim Gibson May 04 '12 at 13:38
Yes, that's correct. Although for absolute clarity it's the textual content of description:GDataMediaDescription 0xc132880: – Tim Gibson May 04 '12 at 14:16
Found it!!!!! GDataYouTubeMediaGroup *mediaGroup = [(GDataEntryYouTubeVideo *)entry mediaGroup]; GDataMediaDescription *desc = [mediaGroup mediaDescription]; NSString *mystring = [desc stringValue]; – Tim Gibson May 04 '12 at 14:34
Just now realized that you were working with GData objc client. Yes that is the solution indeed (although we would be more efficient in our answers if we did now about that in the first place :P). – Alladinian May 04 '12 at 14:39

Extracting string from a string in Objective-C

2 Answers2