NSFormatter.md

up, next

NSFormatter

GRMustache provides built-in support for NSFormatter and its subclasses such as NSNumberFormatter and NSDateFormatter.

There are ready-made filters and rendering objects (aka "lambdas").

Filter facet

Just add your formatters to the data you render: they get ready to be used as filters:

Document.mustache:

{{ percent(x) }}

Rendering code:

NSNumberFormatter *percentFormatter = [NSNumberFormatter new];
percentFormatter.numberStyle = NSNumberFormatterPercentStyle;

id data = @{
    @"x": @(0.5),
    @"percent": percentFormatter,
};

NSString *rendering = [GRMustacheTemplate renderObject:data
                                          fromResource:@"Document"
                                                bundle:nil
                                                 error:NULL];

Rendering:

50%

Rendering object facet

Rendering objects are able to render a full Mustache section as they want. NSFormatters take the opportunity to format all variable tags inside the section:

Document.mustache:

{{# percent }}
hourly: {{ hourly }}
daily: {{ daily }}
weekly: {{ weekly }}
{{/ percent }}

Rendering code:

NSNumberFormatter *percentFormatter = [NSNumberFormatter new];
percentFormatter.numberStyle = NSNumberFormatterPercentStyle;

id data = @{
    @"hourly": @(0.1),
    @"daily": @(1.5),
    @"weekly": @(4),
    @"percent": percentFormatter,
};

NSString *rendering = [GRMustacheTemplate renderObject:data
                                          fromResource:@"Document"
                                                bundle:nil
                                                 error:NULL];

Rendering:

hourly: 10%
daily: 150%
weekly: 400%

Variable tags buried inside inner sections are escaped as well, so that you can render loop and conditional sections. However, values that can't be formatted are left untouched:

Document.mustache:

{{# percent }}
  {{# ingredients }}
  - {{ name }}: {{ proportion }}  {{! name is intact, proportion is formatted. }}
  {{/ ingredients }}
{{/ percent }}

Would render:

- bread: 50%
- ham: 22%
- butter: 43%

Precisely speaking, "values that can't be formatted" are the ones that have the stringForObjectValue: method return nil, as stated by apple.

Typically, NSNumberFormatter only formats numbers, and NSDateFormatter, dates: you can safely mix various data types in a section controlled by those well-behaved formatters.

Get inspired

NSFormatter has been turned into a citizen of GRMustache using public APIs: check the code for inspiration.

up, next