Best practices for nil use in Objective-c

It is not necessary to assign nil as the initial value to the variable

NSString *mystring = nil;

The above code is the same as the nil effect, so let's keep it simple:

NSString *mystring;

The same is true for property handling. Remember that nil is equivalent to 0, and the latter is equivalent to a Boolean no, so it does not need to be as follows:

@property (nonatomic, assign) BOOL didLoad; ... didLoad = NO;

It is not necessary to set the initial value to no, because the initial value of all variables is nil, so the value of Didload is No.

Delegate (Delegate)

if (self.delegate) {     if ([self.delegate respondsToSelector:@selector(@ "didFinish" )]) {        [self.delegate didFinish];     } }

This code can also be simplified, when delegate is nil, nil can only receive messages with a value of nil, so the outer layer of judgment is unnecessary and can be simplified as follows:

if ([self.delegate respondsToSelector:@selector(@ "didFinish" )]) {     [self.delegate didFinish]; }

Simplified conditional clauses

if (myObj == nil)

Can be simplified to:

if (!myObj)

Also be careful to avoid using! =:

if (myObj != nil)

It's hard to read and see how simple the following features are:

if(myObj)

A string of objects can also be nil

if (a.b.c)

The above code when any of a, B, C is nil, the value is false, so it is completely OK, so there is no need to write the following:

if (a)      if (a.b)         if (a.b.c)

To keep nil for nil.

I've noticed that I've written a lot of this code before: Initialize an array to an empty array @[] Instead of keeping the array in nil or uninitialized state. But actually keeping them nil is no good. If you have an array object with a value of nil, you check the number of it, and check the number of empty arrays as a result. In the code below, whether myarray is nil or @[], the result of the conditional judgment is true.

if (myArray.count == 0)

Best practices for nil use in objective-c