Swift

label.textAlignment = NSTextAlignment.left 
//or the shorter
label.textAlignment = .left

Any value in the [NSTextAlignment](<https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html#//apple_ref/doc/c_ref/NSTextAlignment>) enum is valid: .left, .center, .right, .justified, .natural

Objective-C

label.textAlignment = NSTextAlignmentLeft;

Any value in the [NSTextAlignment](<https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/index.html#//apple_ref/doc/c_ref/NSTextAlignment>) enum is valid: NSTextAlignmentLeft, NSTextAlignmentCenter, NSTextAlignmentRight, NSTextAlignmentJustified, NSTextAlignmentNatural

Vertical alignment in UILabel is not supported out of the box: http://stackoverflow.com/questions/1054558/vertically-align-text-to-top-within-a-uilabel