Objective c NSMutableArray和自定义NSObject存在问题
在这件事上我真的很绝望。我正在尝试制作一个框架,你可以用它搜索和播放YouTube视频。但是在测试的时候,我遇到了一个大问题 在搜索操作中,我将向NSMutableArray添加视频(NSObject的子类)。当我在main()中循环通过它时,得到的对象为零: 方法Objective c NSMutableArray和自定义NSObject存在问题,objective-c,arrays,nsmutablearray,null,Objective C,Arrays,Nsmutablearray,Null,在这件事上我真的很绝望。我正在尝试制作一个框架,你可以用它搜索和播放YouTube视频。但是在测试的时候,我遇到了一个大问题 在搜索操作中,我将向NSMutableArray添加视频(NSObject的子类)。当我在main()中循环通过它时,得到的对象为零: 方法 - (NSArray *)videosInRange:(NSRange)range { if(range.length > 50) { [NSException raise:@"Range lenth > 50"
- (NSArray *)videosInRange:(NSRange)range {
if(range.length > 50) {
[NSException raise:@"Range lenth > 50"
format:@"The range of -videosInRange: can't be bigger than 50"];
return nil;
}
if((range.location + range.length) > 999) {
[NSException raise:@"Range to big"
format:@"The given range was to big (%d, %d)", range.location, range.length];
return nil;
}
NSString *searchURLString = [[self feedURL] absoluteString];
searchURLString = [searchURLString stringBySettingURLAttribute:@"start-index" value:[NSString stringWithFormat:@"%d",range.location + 1]];
searchURLString = [searchURLString stringBySettingURLAttribute:@"max-results" value:[NSString stringWithFormat:@"%d",range.length]];
NSLog(@"%@",searchURLString);
NSURL *url = [NSURL URLWithString:searchURLString];
NSXMLDocument *xmlDoc = [[NSXMLDocument alloc] initWithContentsOfURL:url
options:0
error:NULL];
if(!xmlDoc)
return nil;
NSArray *videoElements = [[xmlDoc rootElement] elementsForName:@"entry"];
NSMutableArray *videos = [[NSMutableArray alloc] initWithCapacity:[videoElements count]];
register int i;
for(i = 0; i < [videoElements count]; i++) {
NSAutoreleasePool *addPool = [[NSAutoreleasePool alloc] init];
YTVideo *vid = [[YTVideo alloc] initWithXMLElement:[videoElements objectAtIndex:i]];
[videos addObject:vid];
[vid release];
[addPool drain];
}
NSArray *retValue = [NSArray arrayWithArray:videos];
[videos release];
return retValue;
}
我只有在被要求时才能得到标题(和其他视频信息)。-stringByDecodingHTMLEntities工作正常(分类在NSString上)。我已经在
-init
方法中重写了代码并初始化了所有实例变量也许只是标题为nil?我认为YTVideo
中的initWithXMLElement
方法可能有问题。我们可以看一下《YT视频》课程吗?谢谢你的回答,我已经更新了我的问题,你认为这个程序的输出是什么?它是否打印“nil”
,或“(null)”
?它打印(null),但我注意到的另一件事是,当我在main()中的while循环末尾插入break语句时,程序崩溃。调试器的日志:“2主;1 nspoputoreleasepool;0 objc_msgSend”。如果你想让我上传整个项目,我当然愿意这样做!
int main(int argc, const char *argv[]) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
YTSearchFeed *feed = [[YTSearchFeed alloc] initWithSearch:@"Eminem"];
long long results = [feed videoCount];
NSLog(@"%lld videos for search", results);
long long i = 0;
while(results != 0) {
int length = (results >= 50) ? (50) : (results);
NSArray *videos = [feed videosInRange:NSMakeRange(i, length)];
NSLog(@"L: %d", [videos count]);
int z;
for(z = 0; z < [videos count]; z++, i++) {
YTVideo *vid = [videos objectAtIndex:z];
NSString *title = [vid title];
NSLog(@"%d: %@", i+1, title);
}
results -= length;
}
[pool drain];
return NSApplicationMain(argc, argv);
}
- (id)initWithXMLElement:(NSXMLElement *)element {
self = [super init];
if(self != nil) {
_XMLElement = [element copy];
}
return self;
}
- (NSString *)title {
if(!_title) {
NSString *str = [[[self XMLElement] firstElementWithName:@"title"] stringValue];
_title = [[str stringByDecodingHTMLEntities] retain];
}
return [[_title copy] autorelease];
}