您好我使用下面的框架，
#import <MediaPlayer/MediaPlayer.h>
#import <AudioToolbox/AudioToolbox.h>
#import <AVFoundation/AVFoundation.h>
在其中一个按钮事件中，我已经实现了以下代码来打开库。
MPMediaPickerController *mediaPicker = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeMusic];
mediaPicker.delegate = self;
mediaPicker.allowsPickingMultipleItems = YES; // this is the default
[self presentModalViewController:mediaPicker animated:YES];
[mediaPicker release];
并且在MPMediaPickerController的委托方法中实现了如下代码
#pragma mark MPMediaPickerController delegate methods
- (void)mediaPicker: (MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection {
// We need to dismiss the picker
[self dismissModalViewControllerAnimated:YES];
// Assign the selected item(s) to the music player and start playback.
counterIpod = [mediaItemCollection.items count];
totalcollection = counterIpod;
if (totalcollection > 10) {
NSString *str = [NSString stringWithFormat:@"App Only supports importing 10 songs at a time"];
UIAlertView *connectionAlert = [[UIAlertView alloc] initWithTitle:@"Message !" message:str delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[connectionAlert show];
[connectionAlert release];
}
else {
[self performSelector:@selector(saveMediaItem:) withObject:mediaItemCollection afterDelay:0.1];
//[self saveMediaItem:mediaItemCollection];
//[self showLoadingView];
}
}
- (void)mediaPickerDidCancel:(MPMediaPickerController *)mediaPicker {
// User did not select anything
// We need to dismiss the picker
[self dismissModalViewControllerAnimated:YES];
}
#pragma mark Sace Item Collection to documentsDirectory
-(void)saveMediaItem:(MPMediaItemCollection *)mediaItemCollection {
for (int i = 0; i < [mediaItemCollection.items count]; i++) {
[self exportAssetAsSourceFormat:[[mediaItemCollection items] objectAtIndex:i]];
NSLog(@"for loop : %d", i);
}
NSArray *itemsArray1 = appDelegate.mediaItemCollection1.items;
MPMediaItemCollection *mediaItemCollection2;
if ([itemsArray1 count] != 0) {
mediaItemCollection2 = [self collectionByAppendingCollection:mediaItemCollection];
}
else {
mediaItemCollection2 = mediaItemCollection;
}
[self saveMediaItemAfterDeletting:mediaItemCollection2];
}
-(void)saveMediaItemAfterDeletting:(MPMediaItemCollection *)mediaItemCollection {
NSMutableData* data = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:mediaItemCollection forKey:@"my_playlist"];
[archiver finishEncoding];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:@"%@/playlist.data", documentsDirectory];
NSLog(@"file path = %@", filePath);
[data writeToFile:filePath atomically:YES];
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]){
NSLog(@"file exists : ===========>>>>>>>>>>>");
} else {
NSLog(@"file doesn't exist");
}
//NSLog(@"archiving playlist success = %d", success);
[archiver release];
[data release];
[self UpdateMediaCollection];
}
-(NSString*) getExtension:(MPMediaItem *)item {
// [self showLoadingView];
NSURL *assetURL = [item valueForProperty:MPMediaItemPropertyAssetURL];
AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];
// JP
// AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]
// initWithAsset:songAsset
// presetName:AVAssetExportPresetPassthrough];
NSArray *tracks = [songAsset tracksWithMediaType:AVMediaTypeAudio];
AVAssetTrack *track = [tracks objectAtIndex:0];
id desc = [track.formatDescriptions objectAtIndex:0];
const AudioStreamBasicDescription *audioDesc = CMAudioFormatDescriptionGetStreamBasicDescription((CMAudioFormatDescriptionRef)desc);
FourCharCode formatID = audioDesc->mFormatID;
//exportAudioMix.inputParameters = [NSArray arrayWithObject:exportAudioMixInputParameters];
//exportSession.audioMix = exportAudioMix;
NSString *fileType = nil;
NSString *ex = nil;
switch (formatID) {
case kAudioFormatLinearPCM:
{
UInt32 flags = audioDesc->mFormatFlags;
if (flags & kAudioFormatFlagIsBigEndian) {
fileType = @"public.aiff-audio";
ex = @"aif";
} else {
fileType = @"com.microsoft.waveform-audio";
ex = @"wav";
}
}
break;
case kAudioFormatMPEGLayer3:
fileType = @"com.apple.quicktime-movie";
ex = @"mp3";
break;
case kAudioFormatMPEG4AAC:
fileType = @"com.apple.m4a-audio";
ex = @"m4a";
break;
case kAudioFormatAppleLossless:
fileType = @"com.apple.m4a-audio";
ex = @"m4a";
break;
default:
break;
}
return ex;
}
#pragma mark Covert Item separate item collection and store songs into directory
- (void)exportAssetAsSourceFormat:(MPMediaItem *)item {
// [self showLoadingView];
NSLog(@"export asset called");
NSURL *assetURL = [item valueForProperty:MPMediaItemPropertyAssetURL];
NSLog(@"\n>>>> assetURL : %@",[assetURL absoluteString]);
AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];
// JP
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]
initWithAsset:songAsset
presetName:AVAssetExportPresetPassthrough];
NSArray *tracks = [songAsset tracksWithMediaType:AVMediaTypeAudio];
AVAssetTrack *track = [tracks objectAtIndex:0];
id desc = [track.formatDescriptions objectAtIndex:0];
const AudioStreamBasicDescription *audioDesc = CMAudioFormatDescriptionGetStreamBasicDescription((CMAudioFormatDescriptionRef)desc);
FourCharCode formatID = audioDesc->mFormatID;
//exportAudioMix.inputParameters = [NSArray arrayWithObject:exportAudioMixInputParameters];
//exportSession.audioMix = exportAudioMix;
NSString *fileType = nil;
NSString *ex = nil;
switch (formatID) {
case kAudioFormatLinearPCM:
{
UInt32 flags = audioDesc->mFormatFlags;
if (flags & kAudioFormatFlagIsBigEndian) {
fileType = @"public.aiff-audio";
ex = @"aif";
} else {
fileType = @"com.microsoft.waveform-audio";
ex = @"wav";
}
}
break;
case kAudioFormatMPEGLayer3:
fileType = @"com.apple.quicktime-movie";
ex = @"mp3";
break;
case kAudioFormatMPEG4AAC:
fileType = @"com.apple.m4a-audio";
ex = @"m4a";
break;
case kAudioFormatAppleLossless:
fileType = @"com.apple.m4a-audio";
ex = @"m4a";
break;
default:
break;
}
exportSession.outputFileType = fileType;
NSString *fileName = nil;
fileName = [NSString stringWithString:[item valueForProperty:MPMediaItemPropertyTitle]];
fileName = [[fileName stringByAppendingString:@"-"] stringByAppendingString:[item valueForProperty:MPMediaItemPropertyArtist]];
NSArray *fileNameArray = nil;
fileNameArray = [fileName componentsSeparatedByString:@" "];
fileName = [fileNameArray componentsJoinedByString:@""];
NSLog(@">>>>> fileName = %@", fileName);
NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filePath = [[docDir stringByAppendingPathComponent:fileName] stringByAppendingPathExtension:ex];
NSLog(@"filePath = %@", filePath);
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
//NSLog(@"file exist::::::::::==============>>>>>>>>>>>>>>>>>");
counterIpod--;
if(counterIpod == 0) {
//[self showAlertView];
//[self hideLoadingView];
}
NSString *str = [NSString stringWithFormat:@"Loading %d of %d Beats", totalcollection - counterIpod ,totalcollection];
[lbl performSelectorOnMainThread:@selector(setText:) withObject:str waitUntilDone:NO];
//NSLog(@"loading string : %@", str);
return;
}
//NSLog(@"file not exist ===========>>>>>>>>>");
// -------------------------------------
int fileNumber = 0;
NSString *fileNumberString = nil;
NSString *fileNameWithNumber = nil;
while ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
fileNumber++;
fileNumberString = [NSString stringWithFormat:@"-%02d", fileNumber];
fileNameWithNumber = [fileName stringByAppendingString:fileNumberString];
filePath = [[docDir stringByAppendingPathComponent:fileNameWithNumber] stringByAppendingPathExtension:ex];
//NSLog(@"filePath = %@", filePath);
}
// -------------------------------------
myDeleteFile(filePath);
exportSession.outputURL = [NSURL fileURLWithPath:filePath];
[exportSession exportAsynchronouslyWithCompletionHandler:^{
if (exportSession.status == AVAssetExportSessionStatusCompleted) {
NSLog(@"export session completed");
counterIpod--;
NSString *str = [NSString stringWithFormat:@"Loading %d of %d Beats", totalcollection - counterIpod ,totalcollection];
//[self performSelector:@selector(setLabelText:) withObject:str afterDelay:0.02];
[lbl performSelectorOnMainThread:@selector(setText:) withObject:str waitUntilDone:NO];
NSLog(@"loading string : %@", str);
if(counterIpod == 0) {
//[self showAlertView];
//[self hideLoadingView];
}
} else {
NSLog(@"export session error");
counterIpod--;
NSString *str = [NSString stringWithFormat:@"Loading %d of %d Beats", totalcollection - counterIpod ,totalcollection];
[lbl performSelectorOnMainThread:@selector(setText:) withObject:str waitUntilDone:NO];
//return NO;
if(counterIpod == 0) {
//[self showAlertView];
//[self hideLoadingView];
}
}
[exportSession release];
}];
//[appDelegate hideLoadingView];
}
#pragma mark method to delete file from document directory
void myDeleteFile (NSString* path) {
// NSLog(@"file path delete file :::::::::: %@", path);
if ([[NSFileManager defaultManager] fileExistsAtPath:path]) {
NSError *deleteErr = nil;
[[NSFileManager defaultManager] removeItemAtPath:path error:&deleteErr];
if (deleteErr) {
NSLog (@"Can't delete %@: %@", path, deleteErr);
}
}
}
以上代码在iOS 4.0或之前的版本上没有任何错误，但对于iOS 5.0而言，设备崩溃，我无法在过去15天内解决这些问题。
在此先感谢您的帮助。
我已经解决了这个问题，
只是注释掉这一行
fileName = [[fileName stringByAppendingString:@"-"] stringByAppendingString:[item valueForProperty:MPMediaItemPropertyArtist]];
因为有些歌曲是空的艺术家，所以它崩溃...................
这是因为您使用的某些歌曲具有艺术家名称，而某些歌曲具有空白的艺术家名称，因此您尝试在字符串中追加空白名称，这就是应用程序崩溃的原因。
希望你明白我说的话......