OSX ble and xcode clarifications

Question

I have the OSX BLE heartrate example from: https://developer.apple.com/library/mac/samplecode/HeartRateMonitor/Introduction/Intro.html and have a few questions on it:

1) In the Interface Builder, some controls are listed by the Title and others by the control type. For example in the screen shot below, the "SpO2_bind" and the "anothertext" Text Fields are listed by the Title and by the control type Text Field respectively. Why the difference?

2) Why are some controls bound to the property and some to the ivar? For example, the upper left Text Field (in the main window Heart Rate Monitor) is bound to "self.heartRate" (self):

Whereas the bottom right Text Field is bound to "connected" (no self):

3) In centralManager:didDiscoverPeripheral:advertisementData:RSSI, what is the purpose of the NSMutableArray *peripherals and why couldn't the NSMutableArray *heartRateMonitors be used directly?

Answer 1

1) No difference. In Interface Builder, if you give controls that you drag from Object Library into your views a name they are shown by their name in Dock otherwise they're shown by their default names which are the name of Controls such as UITextField. You give name to the controls in Identity tab. Giving name make your searching in the UI easier since it helps you to identify controls by their name that is easy to distinguish such as UserNameTextFiled that gives you an impression that this UITextField is for user to enter his/her username.

2) In 64 bit OS X, by defining a @property you get the equivalent ivar so no need to define both ivar and @property.

The first case is self.heartRate because it is defined as both @property and ivar and and the wind case is only connect because it's defend just as @property, I think.

3) When you have to-many relationship you should use - mutablArrayForKey which returns a proxy object. It's called Key-Value-Coding.

• mutableArrayForKey: Returns a mutable array proxy that provides read-write access to an ordered to-many relationship specified by a given key.