Initializing an Expression

+ expressionWithFormat:

Initializes the receiver with the specified expression arguments.

Example

NSExpression *expression = [NSExpression expressionWithFormat: @"%d*%f",3,3.5];;
NSLog(@"%@",[expression expressionValueWithObject:nil context:nil]);

Output

2014-04-12 06:24:58.061 iOS-Tutorial[2064:a0b] 10.5

+ expressionWithFormat:argumentArray:

Initializes the receiver with the specified expression format and array of arguments.

Example

NSExpression *expression = [NSExpression expressionWithFormat: @"%f*%f" argumentArray:@[@3.4,@3.1]];;
NSLog(@"%@",[expression expressionValueWithObject:nil context:nil]);

Output

2014-04-12 06:27:06.855 iOS-Tutorial[2093:a0b] 10.54

Creating an Expression for a Value

+ expressionForConstantValue:

Returns a new expression that represents a given constant value.

Example

NSExpression *expression = [NSExpression expressionForConstantValue:[NSNumber numberWithDouble:4.2]];
NSLog(@"%@",[expression expressionValueWithObject:nil context:nil]);

Output

2014-04-12 07:23:25.328 iOS-Tutorial[2262:a0b] 4.2

Creating an Expression for a Function

+ expressionForFunction:arguments:

Returns a new expression that will invoke one of the predefined functions.

Example

NSExpression *now = [NSExpression expressionForFunction:@"now" arguments:[NSArray array]];
NSLog(@"%@",[now expressionValueWithObject:nil context:nil]);

Output

2014-04-12 06:50:00.006 iOS-Tutorial[2145:a0b] 2014-04-12 01:20:00 +0000

+ expressionForFunction:selectorName:arguments:

Returns an expression which will return the result of invoking on a given target a selector with a given name using given arguments.

Example

NSExpression *expression = [NSExpression expressionForConstantValue:[NSNumber numberWithDouble:4.2]];
NSExpression *functionalExpression = [NSExpression expressionForFunction:expression selectorName:@"stringValue" arguments:nil];
NSLog(@"%@",[functionalExpression expressionValueWithObject:nil context:nil]);

Output

2014-04-12 07:23:25.330 iOS-Tutorial[2262:a0b] 4.2

Getting Information About an Expression

- arguments

Returns the arguments for the receiver.

Example

NSExpression *now = [NSExpression expressionForFunction:@"now" arguments:[NSArray array]];
NSLog(@"%@",[now arguments]);

Output

2014-04-12 08:07:21.659 iOS-Tutorial[2327:a0b] (
)

- constantValue

Returns the constant value of the receiver.

Example

NSExpression *expression = [NSExpression expressionForConstantValue:[NSNumber numberWithDouble:4.2]];
NSLog(@"%@",[expression constantValue]);

Output

2014-04-12 08:09:29.514 iOS-Tutorial[2377:a0b] 4.2

- expressionType

Returns the expression type for the receiver.

Example

NSExpression *expression = [NSExpression expressionForConstantValue:[NSNumber numberWithDouble:4.2]];
NSLog(@"%@",[expression expressionType]==NSConstantValueExpressionType?@"NSConstantValueExpressionType":@"Not NSConstantValueExpressionType");

Output

2014-04-12 08:11:22.417 iOS-Tutorial[2409:a0b] NSConstantValueExpressionType

- function

Returns the function for the receiver.

Example

NSExpression *now = [NSExpression expressionForFunction:@"now" arguments:[NSArray array]];
NSLog(@"%@",[now function]);

Output

2014-04-12 08:12:08.078 iOS-Tutorial[2423:a0b] now

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