手写控件布局

1. 打开开关 ----> 开始布局
 1     //1. 打开开关
 2      [logoImageView setTranslatesAutoresizingMaskIntoConstraints:NO];
 3     
 4     //2. 开始布局
 5     NSMutableArray *tmpConstraints = [NSMutableArray array];
 6     [tmpConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-70-[logoImageView(==70)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(logoImageView)]];
 7     [tmpConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"[logoImageView(==70)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(logoImageView)]];
 8     [tmpConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"|-40-[forgetPasswordBtn]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(forgetPasswordBtn)]];
 9     [tmpConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[forgetPasswordBtn]-100-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(forgetPasswordBtn)]];
10     
11     [self.view addConstraints:tmpConstraints];