9 super useful tips for iOS development

1. How to quickly check the execution time of a piece of code.

 #define TICK NSDate *startTime = [NSDate date]
 #define TOCK NSLog(@ "Time: %f" , -[startTime timeIntervalSinceNow])

Do this in the code where you want to view the execution time

 TICK
 //do your work here  
 TOCK

2. How to quickly check the number of times a function is called without adding a line of code. As shown below

 This method is suitable for an if method and a for loop, and it will not interrupt the program, and there is no need to add a line of code. But be sure to select the following automatically continue after evaluating actions;

3. When using view scaling, layer.border.width will become jagged as the view is enlarged. To solve this problem, you need to set this property.

 self.layer.allowsEdgeAntialiasing = YES;

4. What do self, #self, and %self stand for in the time profile of the instrument?

The following is a quote from the Internet

"Self is "The number of times the symbol calls itself." according to the Apple Docs on the Time Profiler.

From the way the numbers look though, it seems self is the summed duration of samples that had this symbol at the bottom of its stack trace. That would make:

self: the number of samples where this symbol was at the bottom of the stack trace

% self: the percent of self samples relative to total samples of currently displayed call tree

(eg - #self / total samples).

So this wouldn't tell you how many times a method was called. But it would give you an idea how much time is spent in a method or lower in the call tree."

5. How to quickly add a global exception breakpoint (one step on top of three steps). And add a symbloic breakpoint (one step or three steps on top) Add a breakpoint without using the mouse

You see the picture, right? I didn't need to move the mouse at all to add these breakpoints (forgive me for bragging). I did move the mouse when adding individual breakpoints, but that was intentional so you could see that I was using a mouse.

First of all, All Exception breakpoints are very common. I did this with a shortcut key! By changing the key command + p to add an exception breakpoint, if you want to know how to change it, please check my previous blog!

Then add the shortcut key of symbloic as commnamd + option + \

The shortcut key to add a single line breakpoint is command + \

6. In iOS development, when we communicate with product designers, we often need to capture the screen of the phone or the simulator. We may use the Home button + the power button on the phone, and then transfer it through iPhoto or QQ on the phone. But I will teach you a way to directly use shortcut keys to capture the picture on the phone to the computer desktop.

The specific method is shown in the figure below:

Find viewDebugging in the debug menu of Xcode. Even if the current program is not running, you can directly capture the pictures on the phone and put them on the desktop. (Hahaha, you don’t need to press the buttons on the phone and copy them to the desktop with iPhoto). Young people, do you think this is the end! ? You are still too immature. Who wants to find this debug menu and find the bunch of things below? Of course, you have to change it to a shortcut key. See the picture below for how to do it.

See the bloody red arrow? First, find the debug shortcut menu item, and then change it to ?+?. What if there is a conflict? You don’t know if it affects other shortcuts. What if you change it? (ps: The previous function is show complete list, which is like clicking one ?, so why do you need it?). Why change it to this? Listen to me. You will definitely feel great if you change it to this. (Okay, it will only take a few minutes to send pictures to product designers in the future~~)

7.iOS debugging tips: only display the alignment size and frame of the image.

I remember someone said to display the alignment size before, he did it like this:

"Set a startup parameter UIViewShowAlignmentRects in the project's Edit Scheme and set the parameter value to YES, so that the program can display the view's alignment matrix (alignment rectangle) at runtime."

I looked at it with disdain. Who would use it if it was so complicated? Do you really think I am showing off? Well, you guessed it right. I am showing off. You can see why I am showing off by looking at the following results.

Maybe I switched the images too quickly, so you didn't see the effect clearly. You can try it yourself. You can switch whether to display ShowAlignmentRect at any time, or the size of each control including system controls (for example, the system UIButton will display the size of the internal imageview and the size of the label and then use different colors to distinguish them. The color distinction of Xcode is still quite beautiful)

This is a killer. With this, you don't need to use the lldb I mentioned earlier to display the size and position of your controls. It is convenient and fast. You asked me how I did it. I didn't configure so many parameters, and I was too lazy to remember them. Of course, I used shortcut keys! Careful students may notice that there are showViewFrame and ShowAlignmentRects in the previous screenshot viewDebuging. Of course, clicking these menus will show these effects. Of course, I changed the shortcut keys again. My time is precious.

8. We often use git in our development, and then we modify the file and don't know where the change is wrong. We often need to restore the file, so we may switch to the terminal, or we may directly use Xcode to abandon the file modification. Fortunately, Xcode supports source control better, so we can quickly restore the file by modifying the shortcut keys of these methods. The following are some of my settings. Use them well to improve your efficiency.

For me, the most common ones are to abandon the modification of the current file and abandon the modification of all files, and look through the git history if the current file cannot be rolled back to the correct one when it is modified. These things can play a big role!

9. In iOS, we often encounter some display methods of UIContentMode of imagView. At first, I couldn’t figure it out no matter how hard I tried to remember it. Later, I saw this picture and found that I had found a guiding light. One picture can help you solve a thousand problems. I would like to share it with you here.