Objective-C Programming Study Notes (2)

Objective-C Programming Reading Notes

Chapter 2 numbers, strings, and sets

String Common Operations

Nsstring * str1 = @ "this is string ";

Nsstring * str2 = [str1 substringwithrange: nsmakerange (8, 6)];

Nsange subrange = [str1 rangeofstring: str2];

If (subrange. Location = nsnotfound)

{

Nslog (@ "string not found ");

} Else {

Nslog (@ "string is at index % lu, length is % lu", subrange. Location, subrange. Length );

}

Nsmutablestring * mstr = [nsmutablestring stringwithstring: str1];

Nsuinteger number = [mstr replaceoccurrencesofstring: @ "this is"

Withstring: @ "an example"

Options: Nil

Range: nsmakerange (0, mstr. Length)];

Common Array Operations

Nsarray * books = @ [@ "book4", @ "book1", @ "book2", @ "book3"];

Nsarray * sortedbooks = [books sortedarrayusingcomparator: ^ nscomparisonresult (ID obj1, Id obj2 ){

Return [obj1 compare: obj2];

}];

For (nsstring * book in sortedbooks ){

Nslog (@ "% @", book );

}

Nsmutablearray * array = [@ [@ "1", @ "2"] mutablecopy];

Array [1] = @ "3 ";

Nslog (@ "% @", array [1]);

Nsmutabledictionary * People = [@ {@ "K1": @ "V1"} mutablecopy];

People [@ "K1"] = @ "V2 ";

Nslog (@ "% @", people [@ "K1"]);

Chapter 4 usage documents

Copy files and use nsprocessinfo

Basic file operations: nsfilehandle

Nsfilemanager * fm = [nsfilemanager defamanager manager];

[Nsbundle mainbundle] pathforresource :( nsstring *) oftype :( nsstring *)]

Nsarray * images = [[nsbundle mainbundle] pathsforresourcesoftype: @ "jpg" indirectory: @ "Images"];

Nsurl * url = [nsurl urlwithstring: @ "http://www.google.com"];

Chapter 4 Memory Management and automatic reference count

// When a large number of temporary objects appear in the program

For (I = 0; I <n; ++ I ){

@ Autoreleasepool {

... // Deal with temporary objects

}

}

When the arc encounters a method call, if the method name starts with alloc, new, copy, mutablecopy, or Int, it assumes that the method returns the object owner to the method caller.

Disable arc for a single file
Compiler flags-Fno-objc-Arc

Chapter 4 copying objects