vb.net barcode maker 7: More About Xcode in Objective-C

Encoder QR Code in Objective-C 7: More About Xcode

CHAPTER 7: More About Xcode
Quick Response Code Maker In Objective-C
Using Barcode generator for iPhone Control to generate, create QR Code image in iPhone applications.
www.OnBarcode.com
Creating Code 128 Code Set B In Objective-C
Using Barcode drawer for iPhone Control to generate, create USS Code 128 image in iPhone applications.
www.OnBarcode.com
Figure 7-31. After single stepping
EAN / UCC - 13 Drawer In Objective-C
Using Barcode printer for iPhone Control to generate, create UPC - 13 image in iPhone applications.
www.OnBarcode.com
UCC - 12 Generation In Objective-C
Using Barcode creator for iPhone Control to generate, create EAN128 image in iPhone applications.
www.OnBarcode.com
Figure 7-32. After stepping into a method
ECC200 Drawer In Objective-C
Using Barcode creator for iPhone Control to generate, create DataMatrix image in iPhone applications.
www.OnBarcode.com
Generating UCC - 12 In Objective-C
Using Barcode encoder for iPhone Control to generate, create Universal Product Code version A image in iPhone applications.
www.OnBarcode.com
CHAPTER 7: More About Xcode
Paint Barcode In Objective-C
Using Barcode drawer for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Print EAN-8 Supplement 2 Add-On In Objective-C
Using Barcode creator for iPhone Control to generate, create EAN8 image in iPhone applications.
www.OnBarcode.com
The last button is step out (press T), which will let the current function finish and then return control to you on the next line of the calling function. If you re following along, don t use this one just yet. We ll be looking at some data values in this method in a little bit. Finishing up the tour, the next button (a box with a spray can in it) brings up the Xcode debug window, and the button after that brings up the GDB console, where you can type stuff into the debugger directly. The final control is a pop-up menu that shows the call stack, which is the current set of active functions. If A calls B, and B calls C, C is considered to be at the top of the stack, with B and A below it. If you open the call stack menu now, it will have -[Car setTire:atIndex:], followed by main. That means that main called -setTire:atIndex:. With more complex programs, this call stack, also called a stack trace, can have dozens of entries in it. Sometimes, the best fact learned during a debugging session is, How the heck did this code get called By looking at the call stack, you can see who called whom to get to the current state (of confusion).
QR Code JIS X 0510 Decoder In .NET Framework
Using Barcode reader for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Scanning QR In VB.NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Taking a Look-See
Denso QR Bar Code Generator In VB.NET
Using Barcode encoder for VS .NET Control to generate, create QR Code image in .NET framework applications.
www.OnBarcode.com
Print EAN-13 Supplement 5 In None
Using Barcode generator for Office Word Control to generate, create UPC - 13 image in Office Word applications.
www.OnBarcode.com
Now that you re stopped, what should you do next Usually, when you set a breakpoint or single-step to a particular part of your program, you re interested in the program state the values of variables. Xcode has datatips, similar to the tooltips that tell you what a button does you hover over it. In the Xcode editor, you can hover over a variable, or a method argument, and Xcode pops up a little window that shows the value, as shown in Figure 7-33.
Decode PDF417 In C#
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
GS1-128 Encoder In None
Using Barcode printer for Office Word Control to generate, create GS1-128 image in Office Word applications.
www.OnBarcode.com
Figure 7-33. Xcode datatip
GS1 - 12 Printer In None
Using Barcode creator for Software Control to generate, create UPC A image in Software applications.
www.OnBarcode.com
Barcode Scanner In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Figure 7-33 has us hovering over index. The datatip pops up and shows us the value is zero, as we expect. You can change the value by clicking the zero and typing in a new value. For example, you can type 37, and then do a couple of step over commands to see the program exit from the out-of-bounds index. While you re still in the loop, hover over tires, and you ll get an array. Scoot the mouse down, and hover over the arrow until it expands, showing you all four tires. Next, move down and over the first tire, and Xcode will show the guts of the tire to you. There are no
Create UPC-A In Java
Using Barcode creation for BIRT Control to generate, create GTIN - 12 image in BIRT reports applications.
www.OnBarcode.com
Barcode Printer In None
Using Barcode maker for Online Control to generate, create Barcode image in Online applications.
www.OnBarcode.com
CHAPTER 7: More About Xcode
Scanning ECC200 In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
UPCA Encoder In None
Using Barcode creation for Office Word Control to generate, create UPC Code image in Word applications.
www.OnBarcode.com
instance variables in our tires, so there s not much to see. But if the class had instance variables, they would be displayed and editable. You can see the result of all this hovering and mousing in Figure 7-34.
Figure 7-34. Digging into the program s data
And that s the whirlwind tour of the Xcode debugger. This information, plus huge amounts of your time, should be enough to let you debug any problems you come across. Happy debugging!
Cheat Sheet
We mentioned a lot of keyboard shortcuts in this chapter. As promised, we ve collected them all in one easy place Table 7-1. Feel free to tear out this page before you give the book to someone else, unless you think that would be rude.
Table 7-1. Xcode Keyboard Shortcuts
Keystroke
E [ ]
Description Expand the editor Shift the code block to the left Shift the code block to the right Accept a completion Show the completion menu Cycle through the completions Cycle backward through the completions Move to the next completion placeholder Make a snapshot Move the cursor forward Move the cursor backward Move the cursor to the previous line Move the cursor to the next line Move the cursor to the beginning of the line Move the cursor to the end of the line
(continued)
Tab Esc Control-. (period) Shift-control-. (period) Control-/ Command-control-S Control-F Control-B Control-P Control-N Control-A Control-E
Copyright © OnBarcode.com . All rights reserved.