ios7以上设置UIView的相对布局,用NSLayoutConstraint
self.label = [[UILabel alloc] init];//这里就不用setframe 了,,,因为后边的layoutconstraint会帮你自适应
self.label.text = @"加载中...";
self.label.textColor = [UIColor whiteColor];
self.label.backgroundColor = [UIColor clearColor];
[[self view] setBackgroundColor:[UIColor blackColor]];
[self.loadingAni startAnimating];
[self.view addSubview:self.label];
[self.label setTranslatesAutoresizingMaskIntoConstraints:NO];//一定要加上这句
pConstraint = [NSLayoutConstraint constraintWithItem:self.label //约束目标
attribute:NSLayoutAttributeTop//约束的属性,有top,bottom,left,right,centerX,centerY等
relatedBy:NSLayoutRelationEqual //一般用等于
toItem:self.loadingAni //参照对象,
attribute:NSLayoutAttributeBottom // 参照属性
multiplier:1.0 //倍率,
constant:30.0/3]; //偏移量,偏移量可正可负,右,下为正,左上为负,除以3表示在6plus 上的偏移为30,但在4上面是10,即分辨率缩放
[self.view addConstraint:pConstraint];
pConstraint = [NSLayoutConstraint constraintWithItem:self.label
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0];
[self.view addConstraint:pConstraint];