The first day of "Objective-c learning record"

1.Foundation Frame

Reference a picture

Cocoa can be seen as a collection of many frameworks, including the foundation framework and the Uikit framework in iOS, where the foundation framework is primarily API-ready for program development, and Uikit includes many UI-drawn functions.

2. String manipulation

Initialize string:

NSString *STR1 = [[NSString alloc] init];

STR1 = @ "Hello,ios.";

NSString *STR2 = [[NSString alloc] initwithstring:@ "Hello,ios."];

NSString *STR3 = [[NSString alloc] initwithformat:@ "Age was%i,name is%.2f", 20,56.0f];

NSString *STR4 = [[NSString alloc] initwithutf8string:@ "Hello,ios."];

Format case:

Convert to lowercase

NSLog (@ "%@", [@ "Hello,ios." lowercasestring]);

Convert to uppercase

NSLog (@ "%@", [@ "Hello,ios." uppercasestring]);

First letter uppercase, other lowercase letters

NSLog (@ "%@", [@ "Hello,ios." capitalizedstring]);

Compare strings:

Judging if they are equal

BOOL res = [@ "abc" isequaltostring:@ "abc"];

Size comparison, there are three kinds of results: nsorderedascending/nsordereddescending/nsorderedsame

Nscomparisonresult res = [@ "abc" compare:@ "abc"];

if (res = = nsorderedascending)

NSLog ("Left < Right");

else if (res = = nsordereddescending)

NSLog ("Left > Right");

Else

NSLog ("left = right");

String prefixes and suffixes are judged:

[@ "abcdef" hasprefix:@ "abc"];

[@ "ABCdef" hassuffix:@ "def"];

To find a string:

Nsrange range = [@ "ABCDEFG" rangeofstring:@ "CD"];

if (range.location = = Nsnotfound)

NSLog (@ "not found.");

Else

NSLog (@ ' range is%@ ', Nsstringfromrange (range));//range is {2,2}

String segmentation:

NSLog (@ "%@", [@ "abcdef" substringfromindex:3]);//def

NSLog (@ "%@", [@ "abcdef" substringtoindex:3]);//abc

NSLog (@ "%@", [@ "abcdef" substringwithrange:nsmakerange (2,3)]);//CDE

NSString *str = @ "A.B.C.D.E.F";

Nsarray *array = [str componentsseparatedbystring:@ "];

NSLog (@ "%@", array);//(A,B,C,D,E,F);

Type conversions:

NSLog (@ "%i", [@ "intvalue]);//12

NSLog (@ "%zi", [@ "Hello,ios." length]);//10

NSLog (@ "%c", [@ "Hello,ios." characteratindex:0]);//h

const char *s = [@ ' Hello,ios. Utf8string];

NSLog (@ "%s", s);//hello,ios.

File operation:

Read File contents

NSString *path = @ "/users/shvier/desktop/demo.txt";

NSString *str = [NSString stringwithcontentsoffile:path encoding:nsutf8stringencoding Error:nil];

NSLog (@ "%@", str);//hello,ios.

Write file contents

NSString *path = @ "/users/shvier/desktop/demo.txt";

NSString *str = @ "Hello,ios";

[Str writetofile:path atomically:yes encoding:nsutf8stringencoding error:nil];//atomically represents a one-time write, if an error occurs during writing, Don't write it all up.

The first day of "Objective-c learning record"