FlexLib

中文版

FlexLib is an Objective-C layout framework for iOS. It's based on flexbox model which is standard for web layout. So the layout capability is powerful and easy to use.

With FlexLib, you can write iOS UI much faster than before, and there are better adaptability.

Screenshots
Feature
Advantage
Usage
Hot Preview
Usage For Swift Project
Example
Attribute Reference
FlexLib Classes
Installation
Intellisense
FAQ
About Flexbox
Author
License

Screenshots

This demo is hot preview:

example0

Can you imagine you almost need nothing code to implement the following effect?

example1 example2

Avoid keyboard automatically

example3

iPhone X adaption

iPhoneX

Feature

layout based on xml format
auto variable binding
onPress event binding
support layout attribute (padding/margin/width/...)
support view attribute (eg: bgColor/fontSize/...)
support reference predefined style
view attributes extensible
UILabel fully support rich-text
support modal view
table cell height calculation
support iPhoneX perfectly
support hot preview
auto adjust view to avoid keyboard
keyboard toolbar to switch input field
cache support for release mode
support Swift project
view all layouts in one page (Control+V)
multi-language support

Advantage

The speed of flexbox is much faster than autolayout.

compare result

Flexbox is more general than autolayout. Flexbox is standard for web and it's also used in ReactNative, Weex, AsyncDisplayKit, Android, ...
FlexLib has better readability. View the autolayout written by others is really boring.
For page like the following image, you don't need UITableView any more. Just write everything in one xml. It's much simpler and maintainable.

setting page

The calculation for height of complex UITableViewCell is really boring. With FlexLib, all the calculation is automatically.
FlexScrollView (the subclass of UIScrollView) can manage its contentSize automatically. I'm sure it will save you a lot of time.
To show or hide subview, just set hidden property. All the layout will refresh automatically.
Hot preview is magic. You can see the final effect on device without restart the app.
UILabel support rich-text and onPress for every rich-text part, and it also allow to change rich-text dynamically.

Usage

Use xml layout file for ViewController:

Write layout with xml file.

The following is a demo file:

<?xml version="1.0" encoding="utf-8"?>

<UIView layout="flex:1,justifyContent:center,alignItems:center" attr="bgColor:white">
<UIView name="_test" onPress="onPressTest:" layout="width:40,height:40" attr="bgColor:lightGray"/>
</UIView>

Derive view controller class from FlexBaseVC


@interface FlexViewController : FlexBaseVC
{
    // these will be binded to those control with same name in xml file
    UIView* _test;
}
@end

@implementation FlexViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.navigationItem.title = @"FlexLib Demo";
}
// This function will bind to onPress event
- (void)onPressTest:(id)sender {
    TestVC* vc=[[TestVC alloc]init];
    [self presentViewController:vc animated:YES completion:nil];
}
@end

Now you can use the controller as normal:


    FlexViewController *vc = [[FlexViewController alloc] init];

    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:vc];
    self.window.rootViewController = nav;

    [self.window makeKeyAndVisible];

Use xml layout file for TableCell:

Write layout with xml file. There is no difference than view controller layout except that it will be used for tabel cell.
Derive table cell class from FlexBaseTableCell:


@interface TestTableCell : FlexBaseTableCell
{
    UILabel* _name;
    UILabel* _model;
    UILabel* _sn;
    UILabel* _updatedBy;

    UIImageView* _return;
}
@end
@implementation TestTableCell
@end

In cellForRowAtIndexPath callback, call initWithFlex to build cell. In heightForRowAtIndexPath, call heightForWidth to calculate height


- (nonnull UITableViewCell *)tableView:(nonnull UITableView *)tableView cellForRowAtIndexPath:(nonnull NSIndexPath *)indexPath {

    static NSString *identifier = @"TestTableCellIdentifier";
    TestTableCell* cell = [tableView dequeueReusableCellWithIdentifier:identifier];
    if (cell == nil) {
        cell = [[TestTableCell alloc]initWithFlex:nil reuseIdentifier:identifier];
    }
    return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    if(_cell==nil){
        _cell = [[TestTableCell alloc]initWithFlex:nil reuseIdentifier:nil];
    }
    return [_cell heightForWidth:_table.frame.size.width];
}

Use xml layout file for other view:

Write layout xml file.
Use FlexFrameView to load xml file, you can set frame or make it flexible. After initiation, maybe you need to call layoutIfNeeded before add it to other view.
add this FlexFrameView to other traditional view


    //load TableHeader.xml as UITableView header
    
    CGRect rcFrame = CGRectMake(0, 0, [[UIScreen mainScreen] bounds].size.width, 0);
    FlexFrameView* header = [[FlexFrameView alloc]initWithFlex:@"TableHeader" Frame:rcFrame Owner:self];
    header.flexibleHeight = YES;
    [header layoutIfNeeded];
    
    _table.tableHeaderView = header;

Hot preview

You can see it here

Usage For Swift Project

Adjust 'Podfile' to use frameworks

podfile

Extend your swift class from FlexBaseVC, FlexBaseTableCell, etc
For those variables, onPress events, class, you should declare them with @objc keyword. Like this:

@objc

Example

To run the example project, clone the repo, and open Example/FlexLib.xcworkspace with XCode to run.

Attribute Reference

FlexLib support two kinds of attribute: layout attribute and view attribute. Layout attribute conform with yoga implementation. View attribute can be extensible using FLEXSET macro.

Notice: FlexLib will output log when it doesn't recognize the attribute you provided. So you should not ignore the log when you develop your project.

layout attributes

view attributes