Swift-cocoa error Handling Mode-standby

The swift error handling mode in swift1.x and Swift 2.0 is different in both modes.

The Swift 1.x code error handling mode uses the Cocoa Framework error-handling mode, which is now used by Objective-c, and the do-try-catch error-handling mode is adopted after Swift2.0 .

The following example code reads a string from a file into memory if you use the Swift 1.x error-handling mode code as follows:

 

2. Import Foundation
10. var err:nserror? Define optional Nserror? variables
18. Let contents = nsstring (contentsoffile:filepath,
22. êencoding:nsutf8stringencoding, Error: &err)
30. If err! = Nil {//determine if the ERR variable is still nil
34. Error handling
38. }

Nserror? must be an optional variable, because you want to initialize it to nil.

Determine If the ERR variable is still nil, if it is nil in the code

 

1. Let contents = nsstring (contentsoffile:filepath,
3. êencoding:nsutf8stringencoding, Error: &err)

No error occurred during method call, otherwise an error occurred.

The constructor for the above code, its swift syntax is defined as follows:

 

1. Init? (Contentsofurl Url:nsurl,
3. Encoding Enc:uint,
5. Error Error:nserrorpointer)

The last parameter of the constructor is Nserrorpointer (that is , the nserror pointer), then we need to pass the Err variable address (that is, &err) in the actual call ,& is the address character. The ERR variable is assigned a value if there is an error after the method call is complete .

Swift-cocoa error Handling Mode-standby