What is NSLog in Objective-C?

What is NSLog in Objective-C?

NSLog outputs the date, time, process name, process ID, and thread ID in addition to the log message. printf just outputs the message. NSLog requires an NSString and automatically adds a newline at the end. printf requires a C string and does not automatically add a newline.

How do I print a statement in Objective-C?

In order to print logs, we use the NSLog method in Objective-C programming language which we have used right from the Hello World example. Now, when we compile and run the program, we will get the following result. 2013-09-16 00:32:50.888 demo[16669] Hello, World!

How do I print a boolean in Objective-C?

Objective-C Language Logging NSLog and BOOL type

There is no format specifier to print boolean type using NSLog. One way to print boolean value is to convert it to a string. Another way to print boolean value is to cast it to integer, achieving a binary output (1=yes, 0=no).

How do you print double values in Objective-C?

We can print the double value using both %f and %lf format specifier because printf treats both float and double are same. So, we can use both %f and %lf to print a double value.

Where can I find NSLog?

Go to View > Debug Area > Activate Console (From your Menu Bar) Or press ⌘ ⇧ C on your keyboard.

Where does NSLog write to?

NSLog outputs messages to the Apple System Log facility or to the Console app (usually prefixed with the time and the process id).

What is NSString?

A static, plain-text Unicode string object that bridges to String ; use NSString when you need reference semantics or other Foundation-specific behavior.

What is a boolean Swift?

Swift uses only simple Boolean values in conditional contexts to help avoid accidental programming errors and to help maintain the clarity of each control statement. Unlike in other programming languages, in Swift, integers and strings cannot be used where a Boolean value is required.

What is double data type example?

The range of double is 1.7E-308 to 1.7E+308. Double data can be represents in real number (1, 10), decimals (0.1, 11.002) and minus (-1, -0.00002). It can hold approximately 15 to 16 digits before and after the decimal point. For example, 4.5672, 2.45354, -5.22234, 3.12345678901, 0.15197e-7 etc.

Should I use float or double?

double has higher precision, whereas floats take up less memory and are faster. In general you should use float unless you have a case where it isn’t accurate enough. On typical modern computers, double is just as fast as float.

What is NSLog in Swift?

NSLog : NSLog adds a timestamp and identifier to the output, whereas print will not; NSLog statements appear in both the device’s console and debugger’s console whereas print only appears in the debugger console.

How do I see log in Xcode?

2. Open the Tools directory and select: Android SDK Tools. Android SDK Platforms-tools.
…
Steps on how to collect XCODE logs:

1. Connect your iOS device to your Mac and then open Xcode. Select Window > Devices.
2. Screen will pop-up which has a list of devices connected to MAC machine.
3. Select the device and then collect the logs.

How do you log an object in Swift?

SwiftLog – A Logging API package for Swift
The usage is really straightforward. First you have to import the Logging framework, then you create a logger and you use that logger instance to print out various log messages. import Logging let logger = Logger(label: “app-identifier”) logger.info(“Hello World!”)

How do I print a console log in Swift?

Logging options in Swift

1. print.
2. NSLog.
3. os_log.
4. To open the Console.
5. You then need to ensure that info and debug messages will show up in the console by going to the Action menu and making sure Include Info Messages and Include Debug Messages are both ticked.

What is the difference between string and NSString?

Secondly, in Swift String is a struct, while in Objective-C, NSString is a class and inherit from NSObject . In concept, Swift String is more likely immutable. If we use a struct type and constant (remember the let keyword), we can keep out a lot of consideration of multi-thread programming and make us a better life.

How do I append to NSString?

Working with NSString. Instances of the class NSString are immutable – their contents cannot be changed. Once a string has been initialized using NSString, the only way to append text to the string is to create a new NSString object. While doing so, you can append string constants, NSString objects, and other values.

What does == mean in Swift?

double-equals operator
== Operator in Swift. The double-equals operator (==) in Swift is used to check if two values are equal. For example: let num1 = 2. let num2 = 2.

What does += mean in Swift?

addition assignment operator
Like C, Swift provides compound assignment operators that combine assignment ( = ) with another operation. One example is the addition assignment operator ( += ): var a = 1. a += 2. // a is now equal to 3.

What is a float vs double?

A float has 7 decimal digits of precision and occupies 32 bits . A double is a 64-bit IEEE 754 double-precision floating-point number. 1 bit for the sign, 11 bits for the exponent, and 52 bits for the value. A double has 15 decimal digits of precision and occupies a total of 64 bits .

What is faster float or double?

Floats are faster than doubles when you don’t need double’s precision and you are memory-bandwidth bound and your hardware doesn’t carry a penalty on floats. They conserve memory-bandwidth because they occupy half the space per number.

Why is double faster than float?

Because float is smaller; double is 8 bytes and float is 4 bytes. +1 for making the effort to do some timings.

How do I collect iOS logs?

Connect your iOS to your computer with a USB or Lightning cable. Go to Window > Devices and select your device from the list. Click the “up” triangle at the bottom left of the right hand panel. All logs from all apps on the device will be displayed here.

What is difference between Array and NSArray?

Array is a struct, therefore it is a value type in Swift. NSArray is an immutable Objective C class, therefore it is a reference type in Swift and it is bridged to Array<AnyObject> . NSMutableArray is the mutable subclass of NSArray . Because foo changes the local value of a and bar changes the reference.

How do I add two strings in Objective C?

The format specifier “%@” is used to insert string values. The example below uses a combination of whitespace and %@ format specifiers to append two strings to string1: NSString * string3 = [string1 stringByAppendingFormat:@” %@ %@”, string2, @”A third string.

What is == and === in Swift?

and === are identity operators and are used to determine if two objects have the same reference. Swift also provides two identity operators (=== and ! ==), which you use to test whether two object references both refer to the same object instance.