IOS开发一些小技巧

[[UIApplication sharedApplication]setStatusBarOrientation:UIInterfaceOrientationLandscapeLeft animated:YES];
CGFloat duration = [UIApplication sharedApplication].statusBarOrientationAnimationDuration;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:duration];

view.transform = CGAffineTransformMakeRotation(-M_PI/2);

static UIImage *shrinkImage(UIImage *original,CGSize size)
{
CGFloat scale = [UIScreen mainScreen].scale;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, size.width*scale, size.height*scale, 8, 0, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, size.width*scale, size.height*scale), original.CGImage);
CGImageRef shrunken = CGBitmapContextCreateImage(context); www.2cto.com
UIImage *final = [UIImage imageWithCGImage:shrunken];

CGContextRelease(context);
CGImageRelease(shrunken);

return  final;
}

这个主要就是返回一个绝对路径用来存放我们需要储存的文件。
- (NSString *)dataFilePath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
return [documentsDirectory stringByAppendingPathComponent:@"shoppingCar.plist"];
}
NSFileManager* fm=[NSFileManager defaultManager];
if(![fm fileExistsAtPath:[self dataFilePath]]){
//下面是对该文件进行制定路径的保存
[fm createDirectoryAtPath:[self dataFilePath] withIntermediateDirectories:YES attributes:nil error:nil];
//取得一个目录下得所有文件名
NSArray *files = [fm subpathsAtPath: [self dataFilePath] ];
//读取某个文件
NSData *data = [fm contentsAtPath:[self dataFilePath]];
//或者
NSData *data = [NSData dataWithContentOfPath:[self dataFilePath]];
}