Tuesday, December 4, 2012

iOS 6's Social Network integration

First thing I want to say: Really appreciate Apple for putting efforts to embed the social sharing functions into the iOS SDK 6.0. You know what, thousands of lines of code I used to do social sharing can be totally deleted now. Wow! It can be just less than 10 lines of code now.

To bring out the Sharing Panel above, we just need to write the code:

- (IBAction) shareButtonClicked:(id)sender{
    NSString *textToShare = @"Hello World!";
    UIImage *imageToShare = [UIImage imageNamed:@"ss.jpg"];
    NSArray *activityItems = @[textToShare, imageToShare];
    UIActivityViewController *activityVC =
    [[UIActivityViewController alloc] initWithActivityItems:activityItems
    [self presentViewController:activityVC animated:YES completion:nil];

UIActivityViewController is under UIKit, so we don't need to include any framework. What we did here was to supply the activitiyVC with a string and an image, and leave all the rest to UIActivityViewController.

Sometimes, we may not provide the sharing panel to user. If we just want to present user the facebook sharing, then we can simply user the following code:

- (IBAction)facebookShare:(id)sender{
    // need include social.framework
    SLComposeViewController *facebookPostVC=[SLComposeViewController composeViewControllerForServiceType:SLServiceTypeFacebook];
    // You can have other servicetypes for Weibo, Twitter.

    [facebookPostVC setInitialText:@"Hello World!"];
    [facebookPostVC addImage:[UIImage imageNamed:@"ss.jpg"]];
    [self presentViewController:facebookPostVC animated:YES completion:nil];


Very similarly, very simple codes...You will get something as following directly. As I comment in the code, we can do the same way for Twitter and Weibo. To use SLComposeViewController, we need to include Social.framework

Very simple right. I love this. However, we have to realize the drawbacks. Good things don't come out without cost... Doing this way, we have no more deep link to Facebook, no need to create App on developers.facebook. So people won't see the feed comes from your App.

Sunday, November 4, 2012

UITextField with Input from UIPickerView

Sometimes, we need an UITextField whose input is picking from an array of strings. People may popup an UIPickerView from an UIActionSheet/UIPopoverController, but it is easier to use UITextField's inputView to do this. Doing this way is more intuitive and more OOP. I would like to achieve something shown below.

To do this, I created a subclass of UITextField, called PickerTextField

In the header file, we can see it is a direct subclass from UITextField. I created some varibles: 1. sourceStringsArray to hold the array of strings to select from; 2. picker to be the inputView of the TextView. 3. pickedIndex to indicated the selected index.

pickedIndex is also declared as a property, used to be an API from other class to access it. You may wondering, how can we access the text from outside? Super easy. my_sub_class.text will give you the text, just like a normal UITextField.

The method:'{setDataSource: andPlaceHolder:}' is an important method for us to set the sourceStringsArray and the textfield's placeholder property.

First two methods are initialization, they won't be called at the same time. Please refer to the comment in the code. Also note '[super setDelegate:self];', which direct the UITextField's delegate to this subclass itself.

'{setDataSource: andPlaceHolder:}' as mentioned earlier, used to assign sourceStringsArray. It has to be called before using it. Besides, we also setup the picker here, and assign the UITextField's inputView to the picker.

 if (self.pickedIndex!=-1) {
        [self setText:[sourceStringsArray objectAtIndex:self.pickedIndex]];
If you want pre-select certain element for the PickerTextField, you call assign a pickedIndex before calling the method.

The remaining code is quite straight forward. UIPickerView's delegate methods. We change the pickedIndex and the text when the picker's selection changes. The following class is only to serve as the mid-object to forward UITextFieldDelegate methods to the PickerTextField. We pre-select first element, if pickerIndex is not assigned with any value and remains -1. I tried to simply use'[super setDelegate:self]' in PickerTextField, but that will lead to infinite loop, end up have to create the PickerTextFieldHandler class to forward.

You can also download the code from git.

Friday, July 27, 2012

Size of iPhone's Photo

Device Photo Size Photo's w:d Ratio Instagram High Resolution Instagram Low Resolution
iPhone 4S 2448 x 3264 3:4 2048 x 2048 612 x 612
iPhone 4 1936 x 2592 3:4 1936 x 1936 612 x 612
iPhone 3GS 1536 x 2048 3:4 1536 x 1536 612 x 612
Recently, I need to do some research about iPhone's photoing functions. Have some figures consolidated here to share with you and also for referring back by myself.

We all know iPhone's screen size is 320 x 480 (640 x 960 for retina), and the ratio is 2:3. Physical screen's w:h ratio 2:3 and photo's w:h ratio 3:4 is close to each other, but the difference is there. If we compare these two ratios, we will find that the photo has more width. People may seldom realize the difference because Apple has done intelligent handling when you are taking the photo with the "Camera App" and when you are viewing the photo with the "Photos App".

When you use the "Camera App" to take a photo, the preview live screen has a width=320px and a height=480px-53px (the camera controls is around 53px) =427px;320:427 is about the same as 3:4. So the preview screen and the photo's w:h ratio is the same, you get exactly what you see in the live preview captured in the photo without any distortion.

Let's see what happens when you open the photo from the "Photos App". Most likely you enter the full-screen mode. Oops, how come the photo with w:d=3:4 just fits into the iPhone's screen with w:d=2:3? The secret is it doesn't really fit. When you zoom out, you will find out the full-screen photo hides small parts at left and right while fits in the height only.

When talking about iPhone photo, have to mention Instagram. Instagram is a great app with simplicity, power, fun. Instagram's photos are all square shape, no need to worry about the ratios. All images are cropped into square before processing.

Thursday, May 31, 2012

Map of iOS SDK Frameworks

I recently saw a map of iOS SDK Frameworks, and was surprised by the author's mindful effort to create it. This map should have come from Apple's developer site or xCode, but it never happened.

I problems when develop an App with lastest iOS SDK but support old iOS (e.g. base SDK: iOS 5.1,  Deployment Target: iOS4.0). When I create functions whose API is only available for iOS 5.0+, that will be a problem if I dont have this map in mind.  With the map in mind, I will be aware that I need to do some API checking before using. 

Class cls = NSClassFromString (@"UIDocument");
if (cls) {
    // Create an instance of the class and use it.
} else {
    // Alternate code path to follow when the
    // class is not available.
As an iOS developer, this map also help me to evaluate my skills by checking whether I am familiar with all the listing frameworks.

 the map is created by 德鲁伊@cocoachina.com(Ref)