Object-C 中各数据类型转换 NSData转NSString，Byte，UIImage

1，NSData 与 NSString

　　NSData --> NSString

　　NSString *aString = [[NSString alloc] initWithData:adata encoding:NSUTF8StringEncoding];

　　NSString --> NSData

　　NSString *aString = @"1234";

　　NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

2，NSData 与 Byte

　　NSData --> Byte

　　NSString *testString = @"1234567890";

　　NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];

　　Byte *testByte = (Byte *)[testData bytes];

　　Byte --> NSData

　　Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};

　　NSData *adata = [[NSData alloc] initWithBytes:byte length:24];

3，NSData 与 UIImage

　　NSData --> UIImage

　　UIImage *aimage = [UIImage imageWithData: imageData];

　　//例：从本地文件沙盒中取图片并转换为NSData

　　NSString *path = [[NSBundle mainBundle] bundlePath];

　　NSString *name = [NSString stringWithFormat:@"ceshi.png"];

　　NSString *finalPath = [path stringByAppendingPathComponent:name];

　　NSData *imageData = [NSData dataWithContentsOfFile: finalPath];

　　UIImage *aimage = [UIImage imageWithData: imageData];

　　UIImage－> NSData

　　NSData *imageData = UIImagePNGRepresentation(aimae);

4，NSData 与 NSMutableData

　　NSData --> MSMutableData

　　NSData *data=[[NSData alloc]init];

　　NSMutableData *mdata=[[NSMutableData alloc]init];

　　mdata=[NSData dataWithData:data];

5，NSData合并为一个NSMutableData

- (NSString *)filePathWithName:(NSString *)filename

{

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory = [paths objectAtIndex:0];

return [documentsDirectory stringByAppendingPathComponent:filename];

}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

//音频文件路径

NSString *mp3Path1 = [[NSBundle mainBundle] pathForResource:@"1" ofType:@"mp3"];

NSString *mp3Path2 = [[NSBundle mainBundle] pathForResource:@"2" ofType:@"mp3"];

//音频数据

NSData *sound1Data = [[NSData alloc] initWithContentsOfFile: mp3Path1];

NSData *sound2Data = [[NSData alloc] initWithContentsOfFile: mp3Path2];

//合并音频

NSMutableData *sounds = [NSMutableData alloc];

[sounds appendData:sound1Data];

[sounds appendData:sound2Data];

//保存音频

NSLog(@"data length:%d", [sounds length]);

[sounds writeToFile:[self filePathWithName:@"tmp.mp3"] atomically:YES];

[window makeKeyAndVisible];

return YES;

}