How to write a Custom UILabel Class using autolayouts

Question

Hi i am very new for ios. I am creating a project in which i have to deal with number of labels on various screens so i have to created one separate class which was inherited from UILabel . I have set all label properties in that class.

But when i run the app. It shows exception like:

'NSInvalidArgumentException', reason: '*** +[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:] 

my code:-

CustomLabel:-

#import "CustomLabel.h"

@implementation CustomLabel

+(id)getLabel {

    CustomLabel *menu;
    menu = [[self alloc] init];
    [menu setBackgroundColor:[UIColor redColor]];
    [menu setTextColor:[UIColor blackColor]];
     menu.text = @"hjh";

    [menu mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(@200);
        make.height.equalTo(@30);
        make.left.equalTo(@10);
        make.right.equalTo(@-10);
    }];

    return menu;
}

MainViewController:-

#import "MainViewController.h"
#import "CustomLabel.h"


@interface MainViewController ()
{
    CustomLabel * mainLabel;
}

@end

@implementation MainViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    mainLabel = [CustomLabel getLabel];
    [self.view addSubview:mainLabel];
}

@end

Answer 1

The mas_makeConstraints call should be made after label is added to view. Remove this call from +(id)getLabel and add at the time of creation of label.

CustomLabel* mainLabel = [CustomLabel getLabel];
[self.view addSubview:mainLabel];
[mainLabel mas_makeConstraints:^(MASConstraintMaker *make) {
    make.top.equalTo(@200);
    make.height.equalTo(@30);
    make.left.equalTo(@10);
    make.right.equalTo(@-10);
}];