Objective C 相当于 Swift addConstraints？

Question

我是使用代码自动布局的新手。

addConstaints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-16-[v0]-16-|",options:NSLayoutFormatOptions(), metrics:nil ,views:["v0":thumbnailImageView]))

addConstaints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-16-[v0]-16-|",options:NSLayoutFormatOptions(), metrics:nil ,views:["v0":thumbnailImageView]))

我正在尝试使用以下代码在 Objective C 中实现上述 swift 代码，但应用程序在加载时崩溃并出现以下错误

由于未捕获的异常而终止应用程序 'NSInvalidArgumentException'，原因：'无法解析约束格式：期待一个视图 H: |-16-[v0]-16-| ^'

    [self addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|-16-[v0]-16-|" 
options:0 
metrics:nil 
views:NSDictionaryOfVariableBindings(thumbnailImageView)]];

    [self addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat:@"V:|-16-[v0]-16-|" 
options:0 
metrics:nil 
views:NSDictionaryOfVariableBindings(thumbnailImageView)]];

.....

UIImageView * thumbnailImageView = [[UIImageView alloc] init];
        thumbnailImageView.backgroundColor = [UIColor greenColor];
        thumbnailImageView.translatesAutoresizingMaskIntoConstraints = false;

        [self addSubview:thumbnailImageView];


        thumbnailImageView.frame = CGRectMake(0, 0, 100, 100);

Answer 1

NSDictionaryOfVariableBindings 生成与您的 Objective-C 变量名称匹配的变量绑定。所以你需要把约束写成

[self addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|-16-[thumbnailImageView]-16-|" 
options:0 
metrics:nil 
views:NSDictionaryOfVariableBindings(thumbnailImageView)]];

或者您直接跳过 NSDictionaryOfVairableDBindings 并使用：

[self addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|-16-[v0]-16-|" 
options:0 
metrics:nil 
views:@{ @"v0" : thumbnailImageView } ];

这有点像 Swift 版本。（目前手边没有编译器，所以第二部分可能会出现一些小的语法错误。会尽快检查）。

Answer 2

您错误地使用了宏NSDictionaryOfVariableBindings您需要传递变量名

/* This macro is a helper for making view dictionaries for +constraintsWithVisualFormat:options:metrics:views:. NSDictionaryOfVariableBindings(v1, v2, v3) is equivalent to [NSDictionary dictionaryWithObjectsAndKeys:v1, @"v1", v2, @"v2", v3, @"v3", nil]; */

 [self addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|-16-[thumbnailImageView]-16-|" 
options:0 
metrics:nil 
views:NSDictionaryOfVariableBindings(thumbnailImageView)]];

    [self addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat:@"V:|-16-[thumbnailImageView]-16-|" 
options:0 
metrics:nil 
views:NSDictionaryOfVariableBindings(thumbnailImageView)]];

Objective C 相当于 Swift addConstraints？

Objective C equivalent of Swift addConstraints?

objective-c

ios

ios-autolayout