IOS summary_simplified syntax for IOS development

IOS summary_simplified syntax for IOS development

The following simplified method is the new method after IOS6.0

NSNumber

// Simplify the preceding statement:

NSNumber * value1;

Value1 = [NSNumbernumberWithInt: 12345];

Value1 = [NSNumbernumberWithFloat: 123.45f];

Value1 = [NSNumbernumberWithDouble: 123.45];

Value1 = [NSNumbernumberWithBool: YES];

// Simplified statement:

NSNumber * value2;

Value2 = @ 12345;

Value2 = @ 123.45f;

Value2 = @ 123.45;

Value2 = @ YES;

// The packing expression can also be written in a similar way:

NSNumber * piOverSixteen1 = [NSNumbernumberWithDouble: (M_PI/16)];

NSString * path1 = [nsstringstringwithuf8string: getenv ("PATH")];

// Can be abbreviated:

NSNumber * piOverSixteen2 = @ (M_PI/16 );

NSString * path2 = @ (getenv ("PATH "));

// For string expressions, note that the expression value must not be NULL; otherwise, an exception is thrown.

NSArray

// For NSArray initialization, there are a lot of writing methods, which will not be listed here. Let's look at the new writing method directly.

NSArray * array;

Array = @ []; // empty array

Array = @ [a]; // an array of Objects

Array = @ [a, B, c]; // array of multiple objects

// Compiler processing:

Array = @ [a, B, c];

// The code generated by the compiler:

Id objects [] = {a, B, c };

NSUInteger count = sizeof (objects)/sizeof (id );

Array = [NSArrayarrayWithObjects: objects count: count];

// Note that if the, B, and c objects have nil, an exception will be thrown during running. This is different from the original processing method. Be careful when coding.

NSDictionary

// Similarly, there are many initialization methods for the data structure of the dictionary. Let's look at the new method:

NSDictionary * dict;

Dict =@{}; // empty dictionary

Dict =@{@ "key1": @ "value1"}; // dictionary containing a key-Value Pair

Dict = @ {@ "key1": @ "value1", @ "key2": @ "value", @ "key3": @ "value3 "}; // dictionary containing multiple key-value pairs

// The containers built using the preceding method are immutable. To generate a variable container, You can transmit the-mutableCopy message. For example

NSMutableArray * mutablePlanets = [@[

@ "Mercury", @ "Venus", @ "Earth ",

@ "Mars", @ "Jupiter", @ "Saturn ",

@ "Uranus", @ "Neptune"

] MutableCopy];

NSMutableDictionary * dic = [@ {@ "key1": @ "value1", @ "key2": @ "value", @ "key3": @ "value3"} mutableCopy];